Evaluating COVID-19 disease transmission and public health measures in schools: Outbreak investigation guidance

Table of contents

Preamble

This guidance supports high quality investigations that will contribute to public health’s collective understanding of COVID-19 transmission in all types of school settings and the utility of mitigation measures implemented. A systematic approach to outbreak response, including an investigation that examines cases, contacts, their interactions and environment, will help to produce higher quality evidence and will support public health officials in making evidence informed policy decisions.

The guidelines will provide information applicable to any type of outbreak investigation and will highlight specific considerations for outbreaks occurring within an educational setting including daycares and schools.

The intended audience for this guidance is public health personnel who will be directly involved in responding to COVID-19 outbreaks in schools, and more specifically personnel who provide epidemiological support to the investigation. Professionals in this position will have a varied level of experience in communicable disease epidemiology and outbreak response, as well as case and contact management.  This may include federal field epidemiologists from the Canadian Field Epidemiology ProgramFootnote 1, public health officers from the Canadian Public Health Service, as well as public health investigators in local, regional, provincial/territorial and federal public health authorities. This guidance should be an adjunct resource to the relevant local, regional and provincial/territorial public health directives. The mandate for the control of outbreaks is under the purview of the jurisdictional public health authority.

Current knowledge pertaining to outbreaks in school settings

In Canada, there remain opportunities to make important contributions to the emerging evidence base related to COVID-19 in school-aged children and youth, such as:

Epidemiologic investigations of outbreaks, along with public health research, can contribute to the emerging knowledge base that will support answering these and other questions, and lead to improvements in outbreak prevention and control measures.

A framework for outbreak investigations

The key components provided in this guideline provide a framework for investigating COVID-19 activity in or related to schools. These key components are presented sequentially, though these are rarely undertaken in a strictly linear fashion. The components of an outbreak investigation loosely follow a cycle of preparedness, investigation/response and learning. Preparedness activities, including understanding the context in which the outbreak is occurring, ideally take place before the start of an outbreak. However, it is not uncommon that the outbreak investigation brings about a deeper understanding of the context and the capacity to effectively manage and prevent further outbreaks. Investigators may wish to use these steps as a framework to plan their approach to the investigation, and may augment and adapt the steps as needed for the specific circumstances of the outbreak.

The two questionnaires are:

Given recognized resource constraints, it may not be feasible to conduct a comprehensive epidemiologic investigation of every school outbreak within a jurisdiction. Investigators may wish to prioritize investigations of outbreaks where there are readily available cases and contacts to interview; and/or characteristics of epidemiologic interest, such as vulnerable populations at higher risk of acquiring and transmitting COVID-19, high case numbers or severe disease.

Definition of key terms

Index case: The first case of an outbreak of which the public health authority is aware, but may not be the first case in a chain of transmission.

National case definition: A person with laboratory confirmation of infection with the virus that causes COVID-19 performed at a community, hospital or reference laboratory (NML or a provincial public health laboratory) running a validated assay. This consists of detection of at least one specific gene target by a NAAT assay (e.g. real-time PCR or nucleic acid sequencing).

Best date is either the date of illness onset or (if date of illness onset is not available) the date the positive specimen was collected.

Incubation period is up to 14 days. Current estimates of the incubation period range from 1-14 days with median estimates of 5-6 days between infection and the onset of clinical symptoms of the disease.

The communicable period

An epidemiological link is exposure at a common setting, presence at a gathering, or time spent in a common location or venue, where there is reasonable evidence that transmission could have occurred.

Reasonable evidence of transmission at a setting could include:

School refers to educational facilities that teach kindergarten to grade 12. This guidance pertains to a staff or student who is physically attending school. However, investigators may adapt the content to respond to outbreaks in other educational settings, such as daycare facilities.

Staff is a term applied to anyone who regularly works at the school, including administrators, educators, contractors and volunteers.

A contact is someone who has been in contact with a laboratory-confirmed case during the case’s communicable period. An individual risk assessment will identify each contact’s exposure risk level to determine the required public health actions (i.e. identification as a “close contact” in a school setting)  

Physically distanced means that at least 2 metres of physical distance was maintained from others.

Cohort means a defined group of students, staff, or volunteers whose membership does not change from one school day to another, and avoid close contact with members of other cohorts. Cohorting is a strategy to reduce the number of people who come in contact with each other.

Key components: Preparing for an outbreak investigation

Understand and document the school outbreak context

As school cases are introduced from the community, understanding the current local COVID-19 epidemiology is an important consideration when investigating school outbreaks, particularly when trying to understand if there have been multiple introductions of COVID-19 into the school, infection transmission within the school, or a combination.

Understanding characteristics of the school and its population, the infection mitigation strategies in place, and the compliance with these strategies will be important to inform the outbreak investigation. Provinces and territories have different provisions and guidelines for risk mitigation for education and school settings. Additionally, each school board, as well as individual public, private and alternative school and childcare facilities, may function differently and implement different measures. Understanding the unique context and situation of each educational facility will be essential to conducting the outbreak investigation. The standardized investigation questionnaire for the school setting includes a list of questions to prompt a better understand the school context (Appendix I). This information could be collected in advance from local schools or school boards to help local or regional public health authorities prepare for potential outbreaks. This information could also help local schools or school boards prepare the level of documentation needed during outbreak investigation.

Determine outbreak investigation objectives

Early in, or even prior to, an outbreak investigation, objectives should be considered, as these will help focus the investigation. Key questions answered by the investigation will guide the data that are collected and analyses performed. The overarching objective of outbreak management is to identify all cases and contacts associated with the outbreak to limit spread and suppress the outbreak. Typically, this is done in the course of case and contact management, which may not include a formal outbreak investigation. There are additional objectives that are important to consider prior to launching an outbreak investigation, such as:

The role of whole genome sequencing of SARS-CoV-2 may allow for better understanding of transmission in outbreaks by providing insights into whether cases are infected with virus of common or different lineages. Investigators should engage their jurisdictional public health laboratory if whole genome sequencing is desired.

Data collection and management

Data collection tools and management protocols should be established prior to the occurrence of an outbreak.

This guidance is intended to support data collection by providing a supplementary standardized school case investigation questionnaire (see Appendix II). The school case investigation questionnaire includes questions specific to potential contacts and risks in the school setting in order to elicit information about the potential acquisition and transmission of COVID-19 while at school or travelling to school. However, investigators may wish to alter or adapt the questionnaire or its format to suit local needs. The school case investigation questionnaire should augment but not replace standard data elements that are collected on all COVID-19 cases as per the national case report formFootnote 3 as part of routine case investigation or contact tracing. The national case report form includes demographics, risk factors, possible sources of acquisition and outcomes. The school case investigation questionnaire goes into considerably more detail to investigate case exposures as well as contacts in the school setting.

Where possible, case investigation data is captured electronically to save data entry time and reduce risk of transcription errors. Data should be housed in a secure database that allows extraction of data in tabular formats recognized by most statistical software (.csv, .tsv, .xlsx, .xls). In addition to interviews of cases and contacts, other sources of data should be gathered, such as administrative records from the school, class schedules and attendance records, a school map or floor plan, and seating charts. Investigators should, where possible, visit the school and classrooms affected to better envision the outbreak setting.

Data should be managed in a manner that will facilitate analyses desired; for example, if social network analyses will be performed, data on connections between all cases and contacts must be documented. An example of the data structure for social network analysis is provided in Appendix III.

Go.DataFootnote 4 is a free, downloadable data management system designed for case management and contact tracing, produced by the World Health Organization (WHO). Introductory training on Go.Data can be found through the Open WHO training platform.Footnote 5 In the event that a public health authority’s existing case and contact management system can not quickly adapt to new data collection forms, Go.Data may be an option. However, dedicated IT support may be required to set it up.

Key components: A COVID-19 epidemiologic investigation in a school

Case detection linked to a school (index case)

As all laboratory-confirmed cases of COVID-19 are investigated, public health officials, in the course of the investigation, will identify that a case is a student, a staff member or has some other association to a school. The case investigation interview would include assessment of the case’s presence at the school or any school activities while communicable, assessment of whether the case was at the school or a school activity during the incubation period (which would be investigated among other case movements in exploration of potential sources of acquisition), and assessment of the case’s movements and activities during the communicable period to identify potential contacts. The case investigation will result in contacts being identified and assessed, described below.

Public health authorities may use, or may be exploring, various means of being alerted to potential COVID-19 activity within a school. These approaches to early warning/detection, their utility and limitations, are out of scope for this guidance, but warrants consideration when planning for school outbreak response.

Contact investigation and case finding

A situation-specific definition of a close contact will help investigators efficiently target their contact investigation and case finding efforts.

For the purposes of an outbreak investigation, a close contact can be defined as someone who spent 15 minutesFootnote 6 or more within 2 metres of the communicable case, or had direct physical contact with the case or the case’s bodily fluids without the appropriate use of the recommended personal protective equipment (PPE)Footnote 7.

In a school setting, the use of non-medical cloth masks or facial coverings may not change the classification of close contacts, i.e. close contacts who consistently wore a non-medical mask or facial covering at school could be considered close contacts. Factors affecting the risk of transmission need to be considered in determining what constitutes a close contact. Wearing masks during an encounter decreases the risk of transmission. The understanding of the level of risk reduction through the use of non-medical masks and implications for practice is evolving, and local health authorities should consider any emerging evidence in this area when assessing the risk of transmission and public health management.

In contrast, personal protective equipment (PPE) includes medical (surgical) masks, respirators, face shields, gloves, gowns and other equipment worn predominantly by medical personnel to protect them from certain communicable diseases. These are different from non-medical masks and facial coverings, as they are subject to rigorous quality controls to assure their effectiveness. PHAC’s definition of a close contact excludes those who appropriately wore the recommended PPE for the situation. Although PPE may offer some additional protection in a school setting, there may be risk of user error (e.g., use of not properly fitted equipment or self-contamination when putting it on or removing it) among individuals who are not trained in its use. In a school setting, an individual can be considered as a close contact regardless of the type of PPE used.

Given the fact that public health’s understanding of transmission dynamics in a school setting is still emerging, a sensitive definition of close contact for school outbreaks is recommended. A sensitive definition “casts a wider net”, erring on the side of including those contacts who may not have truly been in close contact but is unlikely to miss any true close contacts. This supports case finding and minimizes the risk of missing links in the transmission chain(s). As most schools in Canada are implementing classroom cohorts, in which students and staff are limited in their classroom interactions to one group of fellow students/staff. Exposure risk inside these cohorts need to be assessed, because different school policies, use of masks, setting and other factors within the cohorts can affect the risk of transmission. The understanding of exposure risk is evolving. Depending on that assessment, the local health authority can determine what constitutes a close contact, associated levels of risk of transmission and appropriate management.

The Public Health Agency of Canada, in keeping with other guidelinesFootnote 18, recommends that where risk of exposure is difficult to ascertain based on the aforementioned factors, the entire cohort should be considered as close contacts of a case, if the case was communicable while at school. In addition to members of the cohort, other close contacts include those who shared a close or confined space with the case while communicable, or who shared objects that may have been contaminated with bodily fluids (e.g. saliva, respiratory droplets/discharge) of the communicable case.

Outbreak investigation may require follow up of individuals who do not fulfill the definition of close contact of the case, but are deemed of interest because they are epidemiologically linked to the case.

Public health officials will determine which contacts should be investigated, and in what level of priority, based on information gained from their interview of the case as well as other information sources including those from the school itself, such as cohort lists; attendance records; and classroom layout/floor plan diagrams. Contacts who spent more time with the case, or in closer proximity, should be prioritized for follow-up.

The main reasons to investigate contacts are to:

In order to determine if contacts are themselves cases, they will be screened for symptoms during the interview. Contacts who report COVID-19 symptoms may be referred for testing and/or medical assessment depending on the severity of symptoms reported. As children and youth may be more likely than adults to be asymptomatic cases of COVID-19,Footnote 9 a decision may be made, as part of a school investigation, to refer asymptomatic contacts for COVID-19 testing.

Meticulous and thorough documentation of details obtained during the close contact interview are important for the outbreak investigation, even if the contacts do not go on to become cases. Information about those who do not become cases can inform investigations about transmission dynamics as much as those that do become cases. Investigators must be mindful of the risk of misclassification bias when making comparisons between cases and non-cases. Specifically, if individuals not identified as cases are in fact asymptomatic cases, inferences made about differences between cases and non-cases would be inaccurate. For this reason, testing of contacts may be important to add confidence to the accuracy of classification. Additionally, limitations to the specificity of laboratory testing must be considered. Guidance for understanding COVID-19 test results are provided elsewhere.Footnote 10

Declaration of an outbreak

Depending on jurisdictional definitions, an outbreak in a school may be declared when there are two or more cases of COVID-19 epidemiologically linked to a school within a 14 day periodFootnote 11. This declaration would indicate that early stages of the investigation have led to the hypothesis that there is reasonable evidence of transmission occurring within the specified school setting. Further investigation could be warranted to determine what factors are associated with the cases and what measures must be put in place to stem the outbreak and prevent further transmission. With the detection of subsequent cases of COVID-19 associated with a school, in addition to the case and contact investigation activities described above, the outbreak investigation and response may expand to include additional activities such as the following:

Outbreak case definition

An outbreak case definition will need to be developed for each school outbreak of COVID-19 to identify cases that are part of a specific school outbreak. The definition of a confirmed outbreak case will likely consist of a laboratory confirmed case of COVID-19 who is epidemiologically linked to the school within a specified time frame. Investigators may wish to develop additional definitions (e.g., suspect outbreak case) in order to include individuals who do not meet the outbreak case definition who they also want to track or include in their analyses (e.g., symptomatic individuals who have not been tested).

Data analysis

Descriptive epidemiology

Descriptive analyses should be performed to describe the outbreak in terms of person, place and time. For example, the number of cases, and break down by age, sex, classroom and role in the school (i.e. teacher, student, administrator, etc.) will likely be important initial outputs of analyses; these are often presented in tabular format.

Data visualization techniques can be used as part of descriptive analyses. Gantt style charts can be used to visualize the timing of cases, showing date of symptom onset (or date that the sample was drawn for an asymptomatic case with a positive sample), estimated period of communicability, and estimated exposure period. This can help identify overlaps between cases’ communicable and likely exposure periods and hypothesize about potential transmission chains or transmission events when detailed transmission information is not available. It may also assist with contact tracing by identifying times when communicable cases were present at the school. This sort of data visualization may be most useful when working with a small number of cases, over a limited time frame, with a small number of common exposures. Gantt charts must be interpreted within the context of the local epidemiology and additional information from case interviews.

There are several software options available for creating Gantt charts. A simple version can be created in Microsoft Excel by assigning a row for each case, a column for each day for the time period of interest and shading in each case’s incubation period and period of communicability, assigning different colours to represent likely exposure periods and periods of communicability. The maximum incubation period is assumed as a proxy for the earliest potential exposure date. Investigators may wish to use different shades to demonstrate the period of overlap between the likely exposure period and presumed period of communicability. This time period where a case may be communicable but not yet symptomatic might be of particular interest as the case is likely taking part in their regular activities. An average incubation period of 5 days could also be denoted on the chart because the exposure date and hence incubation period is usually unknown.

A sample Gantt chart of COVID-19 cases in a classroom is shown in Figure 1. In this example, one interpretation is this Gantt chart shows the likely exposure periods and periods of communicability for 8 cases of COVID-19 in a school setting. The first two cases (cases 1 and 6) had symptom onset on the same date, suggesting two simultaneous introductions of COVID-19 into the school. These first two cases’ periods of communicability overlap with subsequent cases’ likely exposure periods, indicating the possibility that transmission occurred between cases at the school. The overlaps of communicable and incubation periods suggest that up to 3 generations of transmission (cases 1 and 6 to cases 2 and 4; cases 2 and 4 to cases 3, 5 and 7; cases 3, 5 and 7 to case 8) could have occurred at the school. It is also possible that two cases (or in fact multiple) with onset on the same (or close) date suggests an unknown common exposure one generation prior. Further investigations would be needed to better understand the potential transmission chains described above.

Figure 1: Sample Gantt chart of 8 COVID-19 cases in a classroom setting

The incubation period (both maximum duration and most likely duration), presumed period of communicability, and date of symptom onset or specimen collection are shown for each case.

Figure 1

Figure 1: Text Description

Definitions of important dates shown:

Incubation period: up to 14 days from exposure to onset of symptoms

Average incubation period: 5 days prior to onset date

Overlap of incubation period and period of communicability: 2 days prior to onset date

Period of communicability for symptomatic individuals: 2 days prior to onset and 10 days post onset or symptom resolution, whichever is longer

Period of communicability for asymptomatic individuals: 2 days prior to specimen collection date and 10 days post laboratory confirmation

Figure 1: A Sample Gantt chart of 8 COVID-19 cases detected in a classroom setting (of note: the start and end points of the earliest incubation periods and latest communicable periods are outside of the time period shown in the Gantt chart).
Case ID Symptom onset date Specimen collection date Incubation period start date Average incubation period start date Period of communicability Overlap of incubation period and period of communicability
1 12 Sept n/a Before 03 Sept 07 Sept 10 Sept to 22 Sept 10 and 11 Sept
2 14 Sept n/a Before 03 Sept 09 Sept 12 Sept to 24 Sept 12 and 13 Sept
3 n/a 21 Sept 07 Sept 16 Sept 19 Sept to 01 Oct 19 and 20 Sept
4 14 Sept n/a Before 03 Sept 09 Sept 12 Sept to 24 Sept 12 and 13 Sept
5 n/a 20 Sept 06 Sept 15 Sep 18 Sept to 30 Sept 18 and 19 Sept
6 12 Sept n/a Before 03 Sept 07 Sept 10 Sept to 22 Sept 10 and 11 Sept
7 20 Sept n/a 06 Sept 15 Sept 18 Sept to 30 Sept 18 and 19 Sept
8 n/a 28 Sept 14 Sept 23 Sept 26 Sept to 05 Oct 26 and 27 Sept

Social network analysis provides a visual depiction of the broader network of cases and contacts and their links. Colour-coding or symbols can be used to differentiate cases from non-cases. Locations or different types of contacts can also be visually depicted (e.g., to differentiate household contacts, classroom contacts, school bus contacts and sports team contacts). This allows users to visually understand how affected students or other individuals are connected, where transmission has/has not occurred, and importantly, where cutting “ties” within a social network can reduce transmission between groups of individuals.

A social network diagram is made up of nodes and edges. Nodes (also sometimes called actors, points, agents, or vertices) can be used to represent individuals (e.g., cases and contacts), institutions, geographic locations, or events. Nodes are connected by edges (also sometimes called ties, links, arcs, or lines) which represent connections and relationships between two nodes. Groups of connected nodes are referred to as components.

Multiple software options are available for visualizing social networks, including specialized social network analysis software such as Gephi or NetDraw. Many statistical software packages have social network analysis functionality, such as, the R epicontacts package. In social network analysis, “nodes” such as cases, contacts or events, are connected to one another with “edges” or lines. Refer to Appendix III for examples of database structure recommended for social network analysis.

Some analytic methods are available for conducting statistical analyses of social networks, such as measuring the overall level of connectivity within a component or to identify nodes that are most central with regards to their connections and their connections’ connections. Outbreak investigators may wish to further explore these analytic methods. However, often, the most value from the use of social network analysis as part of an outbreak investigation comes from visual inspection to:

An example social network diagram is shown below in Figure 2, based on the data sets found in Appendix III. This diagram shows links identified between 2 cases (nodes 2 and 3) e.g., they might sit next to each other in class and not always maintain a distance of at least 2 metres apart. An additional case (node 1) was linked to an event (node 4), e.g., band practice. Two contacts (nodes 5 and 6) were identified as being at the same event, even if they were not named as contacts by the case.

Figure 2: Sample social network analysis diagram of an outbreak, developed from the data sets presented in Appendix III

Figure 2

Figure 2: Text Description

The diagram consists of 6 nodes. Nodes 1, 2 and 3 are cases. Node 4 is an event. Nodes 5 and 6 are contacts.

Node 2 is linked to node 3. Node 1 is linked to Node 4.

Nodes 5 and 6 are linked to Node 4.

If planning to use social network analysis as part of their outbreak investigation, investigators may wish to include social network-related questions as part of their case investigation and contact tracing interviews such as:

Transmission chain diagrams provide a visual depiction of the transmission of infection between cases, with arrows showing directionality, i.e. which case is thought to have infected a subsequent case, where directionality can be determined. The methods used to develop transmission chain diagrams are similar to the methods described above for social network analysis with regards to software options and data management. However, for transmission chains, the nodes would represent cases and the edges would have arrows showing directionality of transmission where directionality is known. An example of a transmission chain diagram is shown in Figure 3. This example maps out 3 generations of transmission. Case 1 is the initial case who likely transmitted COVID-19 to case 7 and case 3. Case 3 likely transmitted the infection to case 9 who likely transmitted the infection to case 4. Case 7 likely transmitted the infection to case 2 and case 6, who in turn likely transmitted the infection to cases 5 and 8. Note: the cases are numbered in the order in which they presented to public health and not necessarily the order in which they became infected or presented with symptoms.

Figure 3: Sample transmission chain diagram showing the suspected transmission chain between 9 cases of COVID-19 (adapted from Dcoatzee, Wikipedia)

The number represents the order in which the cases were identified.

Figure 3

Figure 3: Text Description

Initial transmission: Case 1 to Case 7; Case 1 to Case 3

Secondary transmission: Case 7 to Case 2 and Case 6; Case 3 to Case 9

Tertiary transmission: Case 6 to Case 5 and Case 8; Case 9 to Case 4

It will not always be possible to determine transmission chains, particularly when multiple cases are present or when there have been multiple exposures that could have led to transmission. Potential transmission chains can be identified through known epidemiological links between cases and the timing of symptom onset and contact periods (the use of the Gantt chart described above may be helpful) and can be strengthened with laboratory genomic data showing that cases are linked.

Spatial analysis/visualization can be used to explore the spatial relationships between cases, contacts and their environment. This can be used to examine transmission patterns and how they might be influenced by proximity to contacts and other environmental factors (e.g. airflow, barriers). This could also be used to identify higher risk contacts in order to prioritize contacts for follow-up.

Some examples of how spatial analysis/visualization could be used in school outbreaks include:

In the following example (Figure 4), a visualization of a classroom is used to depict a potential transmission chain and the hypothesis that a fan may have contributed to transmission. The red desk indicates a primary case, with symptoms onset on Sept 22, with three secondary cases with symptom onset dates of September 27 and 28.

Figure 4: Example of a classroom diagram depicting 4 cases of COVID-19, their onset dates and the hypothesized spread in the classroom between a primary case and two secondary cases seated in close proximity to the primary case

Figure 4

Figure 4: Text Description

There is a diagram of a classroom with a teacher’s desk near the entrance to the room. A PlexiGlass barrier is in front of the teacher’s desk. A fan is located directly to the right of the teacher’s desk. The airflow from the fan is depicted as crossing the front of the room from right to left. The student’s desks are arranged in 5 columns and four rows facing the teacher’s desk.

Case identifier Onset date Location (relative to fan)
Primary Case Sept 22 Seat in the first row, in the second column from the fan.
Secondary case1 Sept 27 Seat in the first row, in the third column from the fan. Directly to the left of primary case.
Secondary case2 Sept 28 Seat in the first row, in the fourth column from the fan. Directly to the left of secondary case1.
Secondary case3 Sept 28 Seat in the third row, in the fourth column from the fan, two seats directly behind secondary case 2

Some examples of spatial analyses/visualizations that have been used in COVID-19 outbreaks can be found in two recently published studies. Park et al. (2020)Footnote 12 created a floor plan of an office building floor with a COVID-19 outbreak. It showed the proximity of several of the cases to one another in an open workspace where workers are seated facing one another.

Lu et al. (2020)Footnote 13 created a floor plan of a restaurant where individuals seated at 3 adjacent tables eating at the restaurant at the same time as the index case later developed COVID-19. The floor plan included the seating arrangement of the cases and the airflow from the restaurant air conditioning unit that pushed air across the 3 adjacent tables.

Analytic epidemiology

Descriptive analyses may result in hypothesis generation that requires additional investigative rigor to characterize risk of transmission in the school setting. If a hypothesis emerges in terms of a likely source or means by which transmission occurred, there may be the potential to conduct an observational analytic epidemiologic study such as a cohort or case-control study. Meaningful inferences from analytic studies require adequate statistical power; since school-based outbreaks may be small in terms of case numbers, it may be preferable to pool data across multiple outbreaks within one or more jurisdictions in order to strengthen inferences possible. If there is the potential that outbreak data will be aggregated with data from other schools or jurisdictions, a standard data collection tool and process will be critical to ensuring comparability (see Appendix I and Appendix II). Potential analytic study designs that could be considered for school outbreaks are briefly described below. If you are planning on undertaking an analytic epidemiological study, you may wish to consult additional epidemiological sources and/or request the assistance of a field epidemiologist from the Canadian Field Epidemiology Program.

Retrospective cohort studies assess exposures (risk factors, interventions) and outcomes (e.g., confirmed or suspected COVID-19 infection) in a defined cohort of individuals (e.g., a classroom, a school, a school bus, a cohorted section of a school). A cohort study design can be considered if there are multiple cases within a cohort or school-related network and if the entire closed group can be reached to collect exposure and outcome information. If an entire cohort cannot be reached, a nested case control study might be appropriate. Cohort studies could be used to assess the impact of exposure to different infection control interventions or activities on the outcome of COVID-19 infection. The full study cohort is assessed for risks and exposures to COVID-19 and tested for COVID-19 infection. This allows investigators to assess which exposures likely led to illness. Since there is the possibility of asymptomatic infection, testing all members of the cohort will be important to ascertain the outcome. Outcome measures include the relative risk of becoming a case, as well as attack rates within the cohort.

An example of cohort studies used to investigate school COVID-19 outbreaks can be found in an advance publication by Dub et al (2020).Footnote 14

Case-control studies compare exposures between individuals who have the outcomes of interest (cases) to individuals without the outcome of interest (controls) who have been selected to be compared to the cases. Often controls are matched on characteristics that could otherwise confound the analyses, such as age and sex. Multiple cases from different schools/classes/outbreaks along with matched controls could be pooled as part of a larger study. This might offer an opportunity to assess risk where there are only small numbers of cases in individual schools/classes.

Of note, for both cohort and case-control studies, if the objective of the study is to assess transmission within a school setting, it would be important to consider whether to exclude primary cases if these are known to have contracted the infection elsewhere and introduced it into the school setting.

Interpretation of analyses

Results of analyses need to be interpreted to inform recommendations and public health actions. This includes characterizing the strength of any conclusions or inferences being drawn as well as a discussion of limitations of the analyses. Investigators should consider the following when interpreting their results:

Outputs of epidemiologic analyses, particularly descriptive analyses, may suggest hypotheses that can be explored further with analytic studies. If analytic studies are not feasible, outputs of descriptive epidemiology can still be informative. It can be helpful to validate findings of analyses with members of the school population, who can add additional insights to data interpretation.

Applied epidemiologic research

If a research study is desired, investigators should refer to the designated study protocol if there is one in place, e.g. WHO’s forthcoming guidanceFootnote 15 on conducting prospective case-ascertained investigation in schools. Investigators should consider the need to obtain research ethics approval for this research in their jurisdiction/study setting.

Additional investigations

In addition to routine environmental assessments that might be undertaken in an outbreak setting, there might be a role for looking more closely at school or classroom ventilation as a potential contributor to COVID-19 transmission. The Harvard T.H. Chan School of Public Health has resourcesFootnote 16 on school ventilation including guidance on measuring classroom ventilation rates that might be of use for investigators. Investigators may wish to engage subject matter expertise outside of the public health community, such as from industrial hygienists, engineers or heating, ventilation and air conditioning (HVAC) experts, if transmission via a ventilation system is suspected.

Taking action and risk communication

At the time of development of this guidance, COVID-19 outbreaks in schools in Canada represent a novel and unknown public health challenge. Results of epidemiologic investigations can inform public health practice as well as policy decisions in the education system. Compelling evidence to strengthen or change measures in schools should be presented to those in a position to make such changes, without delay.

Outbreak communication plans should include media relations, and be developed by provinces and territories in concert with the education sector and community stakeholders. Risk communications must follow principles outlined by the jurisdiction for effective outbreak response and mitigation.

Declaring an outbreak over in context of school setting

Investigators should consider guidance on how to declare an outbreak over issued by their respective public health authority. In the absence of such a definition, the national guidance can be applied.

In principle, a COVID-19 outbreak can be declared over 28 days after the last known exposure linked to the outbreak setting, without detection of any new primary cases (i.e., zero new cases epidemiologically linked to the outbreak setting within 14 days).

A period of 28 days is equivalent to two times the maximum incubation period and is expected to confirm the interruption of human-to-human transmission at the outbreak setting. Given the occurrence of asymptomatic cases, a period of 28 days accounts for the potential that a generation of cases could be undetected in a chain of transmission.

If the date of the last known exposure cannot be defined or is unknown, the 28-day period can be counted from the last case’s date of illness onset or (if asymptomatic) the date that the diagnostic laboratory sample was collected. Cases detected through mass testing of asymptomatic contacts during an outbreak should be included when determining the start of the 28-day period to declare an outbreak over. Secondary cases (i.e., cases epidemiologically linked to outbreak cases, but who are not epidemiologically linked to the outbreak setting or location themselves) should not be included in the 28-day period to declare an outbreak over.

Reporting and sharing knowledge

Given the limited evidence and published reports on COVID-19 outbreaks in schools, investigators are encouraged to publish their outbreak reports. Outbreak information can be shared informally within the Canadian public health community by issuing a Public Health Alert on the Canadian Network for Public Health Intelligence (CNPHI). Outbreak reports can also be submitted for publication to the Canada Communicable Disease Report.Footnote 17

Debriefing

Investigators should, if possible, convene officials from the school, the school community and public health to share information and learnings as well as to consider how future outbreak investigations could be improved upon. This can be done formally, through a meeting or focus group, or by online survey. Debriefing the outbreak investigation process can be a positive experience for those involved and can provide closure to an experience that may have been stressful or difficult.

Appendix I: School-based COVID-19 outbreak investigation - school setting questionnaire

Objective: This detailed questionnaire is intended to elicit information about the school environment which may be relevant to a case or outbreak investigation. This questionnaire can be completed by local public health and school administration in advance of an identification of a case of COVID-19 at a school, as it is a reflection of policies in place in a school. Append a school or school board COVID-19 plan if available and relevant. Public health units and jurisdictions are encouraged to modify and customize these templates as appropriate.

Where additional information on specific topics is indicated based on the respondent’s answers to this questionnaire, you will be directed to complete supplementary questionnaires. These supplementary questionnaires can be found in Appendix I: Supplementary questionnaires.

Download and print Appendix I: School-based COVID-19 outbreak investigation - school setting questionnaire in PDF or Word.

General information

  1. Date questionnaire completed (dd/mm/yyyy):
  2. Is school currently experiencing an outbreak?
    • Yes
    • No
    • Unknown

Participant details

  1. Name of participant:
  2. Position/Job title:
  3. Email:
  4. Phone number:

Section 1: School setting characteristics

  1. School name/Identifier:
  2. Address:
    • Number and street:
    • City:
    • Province/territory:
    • Postal code:
  3. School board:
  4. School population:
    • JK
    • SK
    • Grade 1
    • Grade 2
    • Grade 3
    • Grade 4
    • Grade 5
    • Grade 6
    • Grade 7
    • Grade 8
    • Grade 9
    • Grade 10
    • Grade 11
    • Grade 12
  5. Usual number of students:
  6. Usual number of staff:
  7. Current no. of students attending in person daily:
  8. Current no. of staff attending in person daily:
  9. Before-school care program?
    • Yes
    • No        
  10. After school care program?
    • Yes
    • No

Section 2: Use of masks/face coverings at school

1. Does the school have a mask/face covering policy?

  1. Yes
    • If yes, please append or describe policy:
  2. No
  3. Unknown

2. Are all staff required to wear a mask at school?

Teachers

  1. Yes
  2. No
  3. Unknown

Substitute teachers

  1. Yes
  2. No
  3. Unknown

Administrators

  1. Yes
  2. No
  3. Unknown

Custodial staff

  1. Yes
  2. No
  3. Unknown

Health

  1. Yes
  2. No
  3. Unknown

Counseling

  1. Yes
  2. No
  3. Unknown

Other (list):

  1. Yes
  2. No
  3. Unknown

3. Where are staff required to wear masks? (select all that apply)

  1. Classroom
    • Always
    • When unable to physically distance
    • Not required
  2. Hallways
    • Always
    • When unable to physically distance
    • Not required
  3. Washrooms
    • Always
    • When unable to physically distance
    • Not required
  4. Library
    • Always
    • When unable to physically distance
    • Not required
  5. Gymnasium
    • Always
    • When unable to physically distance
    • Not required
  6. Playground / Yard / Outdoor grounds
    • Always
    • When unable to physically distance
    • Not required
  7. Other
    • Always
    • When unable to physically distance
    • Not required

4. Are any staff exempt from wearing a mask?

  1. Yes
    • If yes, please describe:
  2. No
  3. Unknown

5. Are all students required to wear a mask?

  1. Yes
  2. No
    • If no, please indicate grades/classes where masks are not required:
  3. Unknown

6. Where are students required to wear masks? (select all that apply)

  1. Classroom
    • Always
    • When unable to physically distance
    • Not required
  2. Hallways
    • Always
    • When unable to physically distance
    • Not required
  3. Washrooms
    • Always
    • When unable to physically distance
    • Not required
  4. Library
    • Always
    • When unable to physically distance
    • Not required
  5. Gymnasium
    • Always
    • When unable to physically distance
    • Not required
  6. Playground / Yard / Outdoor grounds
    • Always
    • When unable to physically distance
    • Not required
  7. Other
    • Always
    • When unable to physically distance
    • Not required

7. Are any students exempt from wearing a mask?

  1. Yes
    • If yes, please describe:
  2. No
  3. Unknown

8. Are the following people required to wear masks? (select all that apply)

  1. Parents
    • Not allowed on site
    • Always
    • When unable to physically distance
    • Not required
  2. Visitors
    • Not allowed on site
    • Always
    • When unable to physically distance
    • Not required
  3. Contractors
    • Not allowed on site
    • Always
    • When unable to physically distance
    • Not required
  4. Others
    • Not allowed on site
    • Always
    • When unable to physically distance
    • Not required

9. Are any of the people from Q8 above exempt from wearing a mask?

  1. Yes
    • If yes, please describe:
  2. No
  3. Unknown

Section 3: Cleaning

10. Has the school implemented a policy of enhanced cleaning (e.g. increased cleaning frequency)?

  1. Yes
    • If yes, please append or describe policy:
  2. No
  3. Unknown

11. Are the following areas subject to enhanced cleaning?

  1. Single student use areas (e.g. desks, lockers)
    • Yes
    • No
    • Unknown
  2. High touch surfaces (e.g. door knobs, light switches, tables, chairs, keyboards, toys)
    • Yes
    • No
    • Unknown
  3. Washrooms (e.g. door knobs, toilet handles, light switches)
    • Yes
    • No
    • Unknown

12. Please indicate frequency of cleaning:

  1. Single student use areas (e.g. desks, lockers)
    • Frequency (e.g. 2 times)
    • Unit (e.g. per day, per hour)
  2. High touch surfaces (e.g. door knobs, light switches, tables, chairs, keyboards, toys)
    • Frequency (e.g. 2 times)
    • Unit (e.g. per day, per hour)
  3. Washrooms (e.g. door knobs, toilet handles, light switches)
    • Frequency (e.g. 2 times)
    • Unit (e.g. per day, per hour)

Section 4: Personal hygiene

13.Is there daily symptom screening requirement?

  1. Yes
    • If yes, please append or describe the symptom screening policy:
  2. No
  3. Unknown

14. Who is subject to symptom screening? (select all that apply)

  1. Staff
    • Yes
    • No
    • Unknown
  2. Students
    • Yes
    • No
    • Unknown
  3. Parents
    • Yes
    • No
    • Unknown
  4. Visitors
    • Yes
    • No
    • Unknown
  5. Contractors
    • Yes
    • No
    • Unknown
  6. Others:
    • Yes
    • No
    • Unknown

15. Under what conditions would individuals be denied entry to the school? (select all that apply)

  1. If they have symptoms of COVID-19 (symptoms as indicated by the public health authority)
    • Yes
    • No
    • Unknown
  2. If they are a returning traveller from outside the country within their 14 days of self-isolation
    • Yes
    • No
    • Unknown
  3. If they are a returning traveller from outside the province within their 14 days of self-isolation
    • Yes
    • No
    • Unknown
  4. If they are a contact of a known COVID-19 case
    • Yes
    • No
    • Unknown
  5. If a member of their household has symptoms of COVID-19 (symptoms as indicated by the public health authority)
    • Yes
    • No
    • Unknown
  6. If a member of their household is being investigated for COVID-19 (e.g. test result pending)
    • Yes
    • No
    • Unknown

16. Does the school have a hand hygiene policy?

  1. Yes
    • If yes, please append or describe policy:
  2. No
  3. Unknown

17. Is hand sanitizer alcohol based with at least 60% alcohol?

  1. Yes
    • If yes, please describe where the hand hygiene stations are located:
  2. No
  3. Unknown

18. Aside from sinks, are hand hygiene stations (e.g. hand sanitizing) available in school?

  1. Yes
  2. No
  3. Unknown

19. Are hand sanitizing stations available where staff and students eat?

  1. Yes
  2. No
  3. Unknown

Section 5: Managing illness at school

20. Does the school have a policy for managing a staff member or student who develops illness while at school?

  1. Yes
    • If yes, please append or describe the policy or process for managing a symptomatic person at school:
  2. No
  3. Unknown

21. When a staff member or student develops symptoms of COVID-19 at school, which of the following are required? (select all that apply)

Mask/face shield use by the symptomatic individual

  1. Yes
  2. No
  3. Unknown

Mask/face shield use by anyone taking care of the symptomatic individual

  1. Yes
  2. No
  3. Unknown

Physical distancing between symptomatic individual and persons taking care of symptomatic individual

  1. Yes
  2. No
  3. Unknown

Separate physical location to isolate symptomatic individual until able to leave the school

  1. Yes
  2. No
  3. Unknown

Symptomatic individual must leave the school

  1. Yes
  2. No
  3. Unknown

Section 6: Physical distancing and grouping

22. Have any of the following been implemented to increase physical distancing of students and staff at school? (select all that apply)

Classroom reorganization to allow increased physical distance

  1. Yes
  2. No
  3. Unknown

Class sizes reduced

  1. Yes
  2. No
  3. Unknown

Assigned seating in classes

  1. Yes
  2. No
  3. Unknown

Rotational outdoor time

  1. Yes
  2. No
  3. Unknown

Holding outdoor classes

  1. Yes
  2. No
  3. Unknown

Cohorting or grouping of students, staff or both

  1. Yes
  2. No
  3. Unknown

Washroom assignment by class

  1. Yes
  2. No
  3. Unknown

Limit school-based activities

  1. Yes
  2. No
  3. Unknown

Other (specify):

  1. Yes
  2. No
  3. Unknown

23. Does the school have a policy on substitute teachers?

  1. Yes
    • If yes, please append the policy or describe the COVID-19 restrictions set out for substitute teachers:
  2. No
  3. Unknown

24. Which of the following scenario best describes how interactions are being limited in your school? (Select one of the following)

  1. Generally, students are in the same classroom, with the same classmates all day with the same teacher
    • This applies to grades/classes:
  2. Generally, students are in the same classroom, with the same classmates, all day, with 2 or more teachers coming in and out of the classroom
    • This applies to grades/classes:
  3. Generally, students are in 2 or more classrooms, with the same classmates, during the day with 2 or more teachers
    • This applies to grades/classes:
  4. Generally, students are in 2 or more classrooms, with different classmates, with 2 or more teachers.  
    • This applies to grades/classes:

Section 7: Shared items

25. Does the school have a policy for students to avoid sharing school supplies?

  1. Yes
    • If yes, please append or describe the policy on shared school supplies:
  2. No
  3. Unknown

26. For equipment such as computers, tablets, and other electronics that are shared, is there a policy of cleaning between use?

  1. Yes
    • If yes, please append or describe the cleaning policy for shared electronics:
  2. No
  3. Unknown

27. Are there common supplies as part of classes or extracurricular activities?

  1. Yes
    • If common supplies are used, which supplies and which classes are they used in? (list below)
    • Supplies:
    • Class:
  2. No
  3. Unknown

28. Are supplies cleaned prior to each use?

  1. Yes
  2. No
  3. Unknown

Section 8: Food services

29. Where do students eat their meals and snacks?

30. Where do staff eat their meals and take breaks?

  1. In classroom
  2. In cafeteria
  3. In staff room / department office
  4. Other (specify)

31. Does the school offer food services?

Cafeteria

  1. Yes
  2. No
  3. Unknown

Nutritional programs    

  1. Yes
  2. No
  3. Unknown

Other (specify)

  1. Yes
  2. No
  3. Unknown

Section 9: School bus

32. Approximately what percentage of the student population take the school bus?

  1. List the percentage (%)

33. Does the school bus operator have a COVID-19 plan?

  1. Yes
  2. No
  3. Unknown

Section 10: Additional support

34. Since the start of the school year, has the school ever run out of hand sanitizer?

  1. Yes
    1. If yes, provide the approximate dates of the shortage(s):
  2. No
  3. Unknown

35. Does the school have access to contactless thermometers?

  1. Yes
  2. No
  3. Unknown

36. Does the school have access to COVID-19 testing for staff and students beyond what public health is offering to the general public?

  1. Yes
    • If yes, please indicate:
      • Staff and student given priority access to COVID-19 testing at same facilities as general public
        1. Yes
        2. No
        3. Unknown
      • Staff and student given priority access to COVID-19 testing at designated facilities (e.g. on site)
        1. Yes
        2. No
        3. Unknown

Section 11: Additional information

Please attach or describe any additional relevant information.

Appendix I: School-based COVID-19 outbreak investigation - school-setting questionnaire - supplementary questionnaires

Supplement to section 6: Physical distancing and grouping in a school setting questionnaire

You have indicated that you have implemented physical distancing measures at your school. Please append the related policy if available, and provide further detail by answering the following questions.

Download and print Appendix I: Supplement to section 6: Physical distancing and grouping in a school setting questionnaire in PDF or Word.

Section 1: Classroom reorganization

1. Have classrooms been reorganized to allow for greater physical distancing?

  1. Yes
    • If yes, please append or describe the policy or process for reorganizing the classrooms:
  2. No
  3. Unknown

2. What is the maximum allowable class size and does it differ by grade?

3. Are students assigned seating within a classroom?

Section 2: Cohorts and grouping

4. Does the school use any form of cohorting or grouping of students:

  1. Yes

    If yes, which groups of students are included in a cohort to limit their interactions while at school and how?

    • Specify the grade(s):
      1. By floor
      2. By grade
      3. By class
    • Specify the grade(s):
      1. By floor
      2. By grade
      3. By class
    • Specify the grade(s):
      1. By floor
      2. By grade
      3. By class
    • No
    • Unknown

4a. Notes:

5. Are cohorts organized in a different way than by floor, grades, or class?

  1. Yes

    If yes, please append or describe the cohorting policy:

  2. No
  3. Unknown

6. Do student cohorts include teachers? (select all that apply)

7. What is the maximum allowable size of student cohorts?

8. For student cohorts, describe types of activities, locations and/or spaces in school that may lead to interaction of different cohorts.

9. Does the school use any form of cohorting or grouping of staff

  1. Yes

9a. If yes, which groups of staff are included in a cohort to limit their interactions while at school?

No
Unknown

9b. If yes, please describe how the school is implementing cohorting among staff?

  1. Teaching staff
  2. Administrators
  3. Custodial staff
  4. Health staff
  5. Counseling staff
  6. Other (specify):

Section 3: Communal areas, activities and gatherings

10. Are there visible guides in school for foot traffic (e.g. posting signs, using stanchions and marking floors)?

  1. Yes
  2. No
  3. Unknown

11. Are individual washroom facilities designated by class, cohort, grade, floor or shared by all students and staff?

  1. Yes

    If yes, select all that apply:

    • Designated by class/classroom
    • Designated by cohort
    • Designated by grade
    • Designated by floor
    • Designated for only students
    • Designated for only staff
    • Designated for all students and staff
  2. No
  3. Unknown

12. What is the current policy on school-based activities such as clubs, team sports, and events? (select all that apply)

13. What types of school-based activities are currently happening? (please list below)

  1. Indoor (e.g. gym-sports teams, band, clubs, choir):
  2. Outdoor (e.g. clubs, sports):

14. Does the school have a policy on gatherings of students, such as for assemblies?

  1. Yes

    If yes, is there a limit on size of student/staff gatherings?

    • Max. Number of students:
  2. No
  3. Unknown

15. If yes, please append or describe policy on student gatherings:

Section 4: Outdoor rotation and recess

16. Does the school use rotational outdoor time as a way to reduce risk of COVID-19 transmission?

  1. Yes
  2. No
  3. Unknown

16a. If yes, please select all the ways outdoor time is used:

16b. If yes, please append or describe the policy or process for the use of outdoor time:

17. Does the school have a policy for recess?

  1. Yes
    • If yes, please append or describe the policy.
  2. No
  3. Unknown

18. Do cohorts mix when outside during recess?

  1. Yes
  2. No
  3. Unknown

18a. Please describe how cohorts mix or are prevented from mixing at recess:

Section 5: Additional information

19. For cohorts that include students, describe the types of activities, locations and/or spaces in the school that may lead to interaction between members of different cohorts that have not been investigated in the questions above.

Back to Appendix I: School-based COVID-19 outbreak investigation - school setting questionnaire section 6

Supplement to section 8: Food services in a school setting questionnaire

You have indicated that Food Services are offered at your school. Please provide further details by completing this questionnaire.

Download and print Appendix I: Supplement to section 8: Food services in a school setting questionnaire in PDF or Word.

Section 1: Food services

1. What type of food services are offered at the school?

2. Are shared cutlery, condiments and/or food items available?

  1. Yes
  2. No
  3. Unknown

3. Are lunch and other meal times, and nutritional breaks staggered?

4. If students are eating lunch in the cafeteria or other communal space, is there:

Section 2: Additional information

1. Please provide any additional information you’d like to share:

Back to Appendix I: School-based COVID-19 outbreak investigation - school setting questionnaire section 8

Supplement to section 9: School bus questionnaire

You have indicated that your school has a percentage of the population who uses the school bus. You also indicated you work with a school bus operator who has a COVID-19 plan. Please append the plan if available, and provide further details below.

Download and print Appendix I: Supplement to section 9: School bus questionnaire in PDF or Word.

Section 1: Physical distancing on the bus

1. Have the number of routes changed due to COVID-19?

  1. Yes
  2. No
  3. Unknown

2. Please describe how the school bus routes are organized:

3. Has the school bus capacity changed due to COVID-19?

  1. Yes
  2. No
  3. Unknown

4. Does the school bus use assigned seating?

  1. Yes
  2. No
  3. Unknown

5. Are there school bus boarding and disembarking procedures to support physical distancing?

  1. Yes

    If yes, please describe boarding and disembarking process:

  2. No
  3. Unknown

Section 2: Ventilation and cleaning on the bus

6. Is there a policy on window use/ventilation on the bus?

  1. Yes

    If yes, please describe the policy on window use / ventilation:

  2. No
  3. Unknown

7. Are high contact areas of school buses disinfected (e.g. door handles, window areas, rails, steering wheel, mobile devices and GPS)?

  1. Yes
  2. No
  3. Unknown

8. How frequently are high contact areas of school buses disinfected?

  1. After each route
  2. Between morning and evening pickups
  3. At the end of each day

Section 3: Additional information

9. Please provide any additional information you’d like to share:

Back to Appendix I: School-based COVID-19 outbreak investigation - school setting questionnaire section 9

Appendix II: School-based COVID-19 outbreak investigation - complementary case questionnaire

Download and print Appendix II: School-based COVID-19 outbreak investigation - Complementary case questionnaire in PDF or Word.

Objective

The overarching objective of outbreak investigations is to identify all cases and contacts associated with the outbreak to limit spread and suppress the outbreak. This is accomplished through investigation of outbreak cases and contact tracing. However, additional information gathered during can contribute to the emerging knowledge base related to transmission dynamics, risk factors for introduction and spread, and the effectiveness of the public health interventions and administrative adaptations that have been implemented in particular settings. As schools re-open, information gathered through thorough epidemiological investigations will contribute to our understanding of how COVID-19 may spread in schools, to mitigate COVID-19 infection risk.

This detailed questionnaire should be used in addition to usual case report forms collected on all COVID-19 cases, and may only be implemented at the discretion of the Public Health Authority based on the declaration of an outbreak in a school. It is not intended to be used for single or sentinel cases in a school. Where additional information on specific topics is indicated based on the respondent’s answers to this questionnaire, the interviewer will be directed to complete supplementary questionnaires. These additional modules can be found in Appendix II - Supplementary Questionnaires. It is advised that all questionnaires including all supplementary questionnaires are made readily available and prepared by the interviewer prior to the interview.

This questionnaire is intended to elicit information about an outbreak case’s activities in the 14 days prior to their onset of illness, or positive laboratory test, in order to gather information about potential sources of acquisition at the school. These questions will also help investigators identify contacts in the school or school community who should be assessed for exposure during the case’s period of communicability. Depending on the age and developmental level of the case, a parent or guardian may be required to participate in the case interview. Where possible, memory aids such as calendars, class and transportation schedules, and school board policies should be used to assist the case in recalling the details of their movements/activities. Investigators should exercise discretion when interviewing cases that may have special needs or be unable to wear a mask or maintain physical distancing due to developmental, physical or psychological needs.

Consent to participate

Consent to participate is obtained from interviewees, or proxies (e.g., parents being interviewed on behalf of (or with) their child). Older children and teens may give consent themselves or require parental consent; what is needed and at what age depends on the province or territory of residence. Language should be simplified to the appropriate level for cases and their proxies based on age, language abilities, and understanding.

Definitions

Refer to the Definition of key terms section.

Section 1: Administrative information

  1. Date questionnaire completed (dd/mm/yyyy):
  2. P/T case identifier (link to case report form)
  3. Interviewer’s Name:
    • Position/Job Title:
    • Email:
    • Phone number:
  4. Last Name of Case:
  5. First Name of Case:
  6. Is respondent a proxy? 
    • Yes
      1. If yes, explain reason for proxy:
      2. Proxy’s relationship to case:
    • No
  7. Last Name of respondent:
  8. First Name of respondent:
  9. Email of respondent:
  10. Phone number of respondent:

Introductory script for entire questionnaire

(Interviewer will read to the case or proxy).

Today I will be asking you some questions about your time at work/school over the last few weeks. Public health will use this information to better understand when/where you might have been exposed to COVID-19 and whether there are more things that we can do to keep you and others safe while at work/school. We may ask you to identify other people by name. This is so that we can assess whether they may be at risk for COVID-19 and if they need to be interviewed too. The information you provide is voluntary, and will be kept confidential. Your input is valuable and appreciated. Thank you for taking the time to answer these questions.

The first section of the questionnaire focuses on your/the child’s symptoms.

Section 2: Clinical information

Much of the information collected in this section will have already been collected during the initial public health follow-up. Please consider pre-populating this section and using the case interview as verification.

1. Did you/the child develop symptoms of COVID-19?

  1. Yes
  2. No
  3. Unknown

Symptoms may include one or more of the following: cough, fever (≥38°C), feverish/chills, sore throat, runny nose, shortness of breath/difficulty breathing, nausea/vomiting, headache, general weakness, pain (muscular, chest, abdominal, joint), irritability/confusion, diarrhea.

2. When did symptom(s) first appear?

  1. Date (dd/mm/yyyy):
  2. Asymptomatic

3. When was the positive COVID-19 specimen collected?

  1. Date (DD/MM/YYYY):

Depending on your preferred interview technique, you might want to consider asking open-ended questions about possible COVID-19 exposures.

4. How do you think you were/the child was exposed to COVID-19? Do you know of anyone who has been recently diagnosed with COVID-19?

5. Calculate:

  1. Best date (this date should be used throughout the questionnaire when specified [Best Date])
    1. Date of symptom onset: or
    2. Date of positive specimen collection:     
  2. Incubation period
    1. (14 days prior to [Best Date]) to [Best Date]:      
  3. Communicable period  
    1. 48 hours prior to [Best Date] to full resolution of symptoms or 10 days after [Best Date], whichever is longer:

Introductory script for section 3

(Interviewer will read to the case or proxy).
The next set of questions focuses on your/the child’s time at school before you/the child got sick.

Section 3: School and attendance information

This information is collected to help the investigators understand the setting where the case may have acquired the disease and to enable linkage to other documentation about the school (i.e. school investigation questionnaire).

1. School name or identifier

2. Address:

  1. Number and street
  2. City
  3. Province/territory
  4. Postal code

3. Please indicate your attendance for each school day, in the 14 days prior to [Best Date]: (Provide the following information for each of the 14 days)

  1. Date
    1. Attended
      1. AM
      2. PM
      3. Full day
    2. Did not attend
    3. Not required
    4. Unknown

4. Did you attend the school between [Best Date] and full resolution of your symptoms or 10 days after [Best Date], whichever is longer?

  1. Yes
    1. If yes: Which date(s) did you attend the school?
  2. No
  3. Unknown

5. Are you staff or a student?

  1. Student
    1. Proceed to section 3a student
  2. Staff
    1. Proceed to section 3b staff

Section 3a: Student

The following questions are for a student that is a case of COVID-19:

Whenever possible please consider gathering information from the school and school policy documents in advance of the interview, to help prompt the case/proxy during questioning.

1. Are you able to provide a class schedule?

  1. Yes
  2. No
  3. Unknown

2. What grade/class are you in (e.g., grade 7, class 7B)?

  1. Grade
  2. Class
  3. Room number

3. Are you in the same classroom for all of your classes all day?

  1. Yes
  2. No
    1. If no, please list each of your classes and for each provide the teacher’s name, where it is located, and if it is in the school building or a portable. Please include homeroom if applicable. Also, please include any special education sessions, ISD, guidance meetings, etc that you attended. (If there is more than 1 classroom, please list each class)
      1. Date(s) or day of week if recurring:
      2. Class/session
      3. Teacher
      4. Room number or location
      5. Building or portable
  3. Unknown

Section 3b: Staff

The following questions are for staff that is a case of COVID-19. All questions refer to the 14 days prior to [Best Date].

1. What is your role at the school? Please select all that apply.

  1. Educational worker (teacher, substitute teacher, early childhood educator, educational assistant, child and youth worker)
    1. Complete section 3c: Educational Worker
  2. Role other than educational worker (select all that apply) Continue through this section
    1. Administrator
    2. Office administration
    3. Custodial
    4. Health
    5. Counselling
    6. Lunch supervisor
    7. Food service
    8. Care giver (before/after school)
    9. Bus driver
    10. Other (specify)
  3. Do you work in more than one school/educational setting?
    1. Yes
      1. Please list any additional schools and/or other work settings where you worked in the 14 days prior to [Best Date]. Please also include your role. (If there is more than 1 additional school where you work, please list all)
        1. School
        2. Dates
        3. Role
    2. No
    3. Unknown
  4. Did you spend periods of 15 minutes or more in shared spaces or rooms at this school with other staff or students in the 14 days prior to [Best Date]? This could be an office, gymnasium, cafeteria, library etc.
    1. Yes
      1. Please list the name of the shared space, where it is located and specific dates (if there is more than one, please provide this information for each shared space)
        1. Name of shared space
        2. Location
        3. Building or portable
        4. Dates
    2. No
    3. Unknown

Section 3c: Educational worker

The following questions are for a staff member classified as an educational worker (i.e. teacher, early childhood educator, educational assistant, or child and youth worker) that is a case of COVID-19. All questions refer to the 14 days prior to [Best Date]. Students and other staff skip to Section 4: School shared space exposures, physical distancing and masking.

Depending on your preferred interview technique, you might want to consider asking some open-ended questions in addition to the questions below to gather information about the cases daily work schedule, their classes/groups and their movements during the day.

For example: In general, please describe a typical workday in the 14 days prior to [Best Date]. In your response, it would be helpful if you included information about how you got to school (mode of transportation) the time of day that you typically arrive at the school, where you go when you first arrive at the building and details about how your workday is scheduled/structured. Please also include information about classrooms and other locations within the facility in which you frequently spend time during the day (where you eat your lunch, where you spend preparation time and/or recess time, whether you spent time the gymnasium and/or library).

1. Do you work in more than one school?

  1. Yes
    1. Please list all other schools you work in:
  2. No
  3. Unknown

2. Are you able to share your teaching schedule?

  1. Yes
  2. No
  3. Unknown

3. Please list the grades, class, the classroom, and whether it is inside the school building or a portable for each of your class. Please include homeroom if applicable. (If there is more than 1, please provide information for all the grades and classes you teach)

  1. Grade
  2. Class
  3. Classroom or location
  4. Building or portable

4. When not in the classroom, did you spend periods of 15 minutes or more in shared spaces or rooms at this school with other staff or students in the 14 days prior to [Best Date]? This could be an office, gymnasium, cafeteria, library etc.

  1. Yes
    1. Please list the name of the shared space, where it is located and specific dates (Please provide the following information for all shared spaces)
      • Name of shared space
      • Location
      • Building or portable
      • Dates (within the 14 days prior to onset/diagnosis)
  2. No
  3. Unknown

Introductory script for section 4

(Interviewer will read to the case or proxy).

The next set of questions focuses on where you/your child went while you/your child were at work/school. Please note that more specific questions about masking and physical distancing practices will be asked at the end of the interview.

Section 4: School shared space exposures, physical distancing and masking

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

Wherever possible please consider gathering information from the school related to masking policies in advance of the interview, to help prompt the case/proxy while questioning.

1. Describe the mask wearing policy at your school. Do most of the students and staff follow the policy? Do you/the child follow the policy? If not, please describe.

(Prompts: Do people have to wear a mask all the time or only in certain areas? What type (e.g. non-medical masks)? Which areas? Do you always wear a mask except when you are eating and drinking? Do you wear a mask outdoors? Do you feel like most of the other students and staff where masks in the common areas? Is there anywhere where students and staff never wear masks? In general, do you and others use masks correctly?)

2. Describe the physical distancing policy at your school. Do most of the students and staff follow the policy? Do you/the child follow the policy? If not, please describe.

(Prompts: Do people maintain physical distance of at least 2 metres all the time or only in certain areas? Which areas? Where do they not? Do you always wear a mask if you cannot physically distance? Do you physically distance outdoors? Do you feel like most of the other students and staff physically distance in the common areas? Is there anywhere where students and staff never physically distance?)

3. Are you part of a cohort at school?

A cohort is a group of students, staff, or volunteers whose membership does not change from one school day to another, and avoid close contact with members of other cohorts. Cohorting is a strategy to reduce the number of people who come in contact with each other. Refer to school questionnaire for details around cohorting practices at the school.

4. Outside of your cohort, please name the people you had close, prolonged contact (i.e more than 15 minutes and within 2 metres) with, from two days before [Best Date]: (Please provide the following information for all the people).

5. In which shared spaces (hallways, washrooms, library, cafeteria, etc.) were you most likely not to wear a mask? (select all that apply)

6. In which shared spaces (hallways, washrooms, library, cafeteria or elsewhere) did you notice other students or staff around you were most likely to not wear a mask? (select all that apply)

Introductory script for section 5

(Interviewer will read to the case or proxy).

The next set of questions focuses on mealtimes and the cafeteria at work/school. Please note that more specific questions about masking and physical distancing practices will be asked at the end of the interview.

Section 5: Meals/cafeteria exposures

Applies to all. All questions refer to the 14 days prior to [Best Date].

1. Did you bring your own lunch, use the school food services, eat off-site or go home to eat?

  1. Brought Lunch
  2. Used in school food service
  3. Ate off site
  4. Went home
  5. Other (specify):

2. Did you use any communal food items such as salt/pepper shaker, ketchup, utensils etc.?

  1. Yes
  2. No
  3. Unknown

3. Did you use any communal equipment (fridge, kettle, microwave, coffeepot, etc.),

  1. Yes
  2. No
  3. Unknown

4. On most days, where did you eat your meals?

  1. In classroom
  2. In cafeteria/lunchroom
  3. Outside
  4. Home
  5. Other (specify):

5. On most days did you eat your meals physically distanced from others by at least 2 metres?

  1. Always stay at least 2 metres apart
  2. Sometimes stay 2 meters apart
  3. Never stay 2 metres apart
  4. Can’t remember/don’t know

Introductory script for section 6

(Interviewer will read to the case or proxy).

The next set of questions focuses on how you/the child got to work/school each day. Please note that more specific questions about masking and physical distancing practices will be asked at the end of the interview.

Section 6: Transportation exposures

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

Wherever possible please consider gathering information from the school related to transportation policies in advance of the interview, to help prompt the case/proxy while questioning. Depending on your preferred interview technique, you might want to consider asking some open-ended questions to gather information about the cases mode of transportation, routes, schedules as well as who they sat near/next too during their transportation. It is challenging to recall the movements and actions of others on any given day and therefore it might be useful to ask the case to describe a ‘typical journey’ to and from the educational facility.

1. Please describe in as much detail as possible, how you/ the child traveled to and from the school in the 14 days prior to [Best Date]. Please include information related to the mode of transportation, the schedule, the route and any transfers, as well as information about those sitting near you, and whether they and/or you/the child were wearing masks.

2. In the 14 days prior to [Best Date], how did you/the child get to school each day? Please select all that applies.

  1. Walking / Biking
    Skip to Section 7: Extracurricular activity exposures
    1. Dates
  2. Private vehicle
    Complete Appendix II - section 6a: Private vehicle
    1. Dates
  3. School bus
    Complete Appendix II - section 6b: School bus
    1. Dates
  4. Public transport
    Complete Appendix II - section 6c: Public transportation
    1. Dates
  5. Other (specify) :
    1. Dates

Introductory script for section 7

(Interviewer will read to the case or proxy).

The next set of questions focuses on your/ the child’s extracurricular activities that occur on school grounds, off school grounds but are affiliated with the school, or social activities with others from the school. Please note that more specific questions about masking and physical distancing practices will be asked at the end of the interview.

Section 7: Extracurricular activity exposures

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

1. Did you / the child participate in any extracurricular activities on school grounds (e.g. before/after school care, band, sports, clubs, events, parties, playdates)

  1. Yes
    1. Complete Appendix II - supplement to section 7: Extracurricular activity exposures
  2. No
  3. Unknown

2. Did you / the child participate in any school affiliated extracurricular activities that were held off school grounds?

  1. Yes
    1. Complete Appendix II - supplement to section 7: Extracurricular activity exposures
  2. No
  3. Unknown

Introductory script for section 8

(Interviewer will read to the case or proxy).

The next set of questions focuses on your time at home.

Section 8: At home behaviours and exposures

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

1. Did you do a self-assessment prior to attending school each day?

  1. Always
  2. Sometimes
  3. Never
  4. Don’t remember

2. What is your self-assessment process? Please describe.

3. In the 14 days prior to [Best Date] did any of the following apply to you?

Introductory script for section 9

(Interviewer will read to the case or proxy).

Finally, we would like to ask you/the child about the masking and physical distance practices of you/the child and people around you/the child while you/the child were at work/school.

Section 9: Masking and physical distancing practices - summary

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

1. How often did you/the child wear a mask?

  1. In private vehicle
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  2. Waiting for school bus
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  3. On the school bus
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  4. Waiting for public transport
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  5. On public transport
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  6. School classroom
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  7. School hallways
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  8. School washroom
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  9. School library
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  10. School cafeteria/lunchroom
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  11. School playground/yard
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  12. Office
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  13. During extracurricular activities/events at school
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  14. During before/after school care
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/ unknown
    5. Not applicable
  15. Other (specify):
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable

2. How often did others around you/the child wear a mask?

  1. In private vehicle
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  2. Waiting for school bus
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  3. On the school bus
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  4. Waiting for public transport
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  5. On public transport
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  6. School classroom
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  7. School hallways
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  8. School washroom
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  9. School library
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  10. School cafeteria/lunchroom
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  11. School playground / yard
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  12. Office
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  13. During extracurricular activities/events at school
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  14. During before/after school care
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable
  15. Other (specify):
    1. Always wore mask
    2. Sometimes wore mask
    3. Never wore mask
    4. Do not remember/unknown
    5. Not applicable

3. In which classes and/or activities was it difficult to wear a mask consistently (i.e. lunchtime, snack time)?

  1. Class
  2. Location
  3. Activity

4. How often did you/the child maintain a physical distance of at least 2 metres from others?

  1. In private vehicle
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  2. Waiting for school bus
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  3. On the school bus
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  4. Waiting for public transport
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  5. On public transport
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  6. School classroom
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  7. School hallways
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  8. School washroom
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  9. School library
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  10. School cafeteria/lunchroom
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  11. School playground / yard
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  12. Office
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable
  13. During extracurricular activities/events at school
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/ unknown
    5. Not applicable
  14. During before/after school care
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/ unknown
    5. Not applicable
  15. Other (specify):
    1. Always distanced
    2. Sometimes distanced
    3. Never distanced
    4. Do not remember/unknown
    5. Not applicable

5. In which situations did you find it difficult to maintain physical distance?

  1. Class
  2. Location
  3. Activity

6. Any further comments before we end the interview?

Appendix II: School-based COVID-19 outbreak investigation - complementary case questionnaire - supplementary questionnaires

Supplement to section 4: School cohort/classroom exposure

Download and print Appendix II: Supplementary questionnaire to section 4: School cohort/classroom exposure in PDF or Word.

Section 4: School cohort/classroom exposure

Applies to all cases who are in a cohort. All questions refer to the 14 days prior to [Best Date].

Wherever possible please consider gathering information from the school related to cohorting/grouping policies in advance of the interview, to help prompt the case/proxy while questioning.

1. Is there a name to identify your cohort? (append a list of members):

2. Select the best description of your cohort:

  1. Always the same people in the cohort
  2. Sometimes the same people in the cohort
  3. Never the same people in the cohort (always changing)
  4. Don’t remember / unknown

3. Can you describe your cohort generally? (i.e., number of people, does it include a mix of teachers/staff and students, are there class cohorts and then “study-cohorts” or “sub-cohorts” as well, etc.)

4. To the best of your knowledge, has any student or teacher/staff in your cohort had symptoms of COVID-19?

  1. Student
    1. Yes
      1. Name
      2. Classes shared with case
    2. No
    3. Unknown
  2. Teacher
    1. Yes
      1. Name
      2. Classes shared with case
    2. No
    3. Unknown
  3. Staff
    1. Yes
      1. Name
      2. Classes shared with case
    2. No
    3. Unknown

5. To the best of your knowledge, has any student or staff in your cohort been diagnosed / have a positive test of COVID-19?

  1. Student
    1. Yes
      1. Name
      2. Classes shared with case
    2. No
    3. Unknown
  2. Teacher
    1. Yes
      1. Name
      2. Classes shared with case
    2. No
    3. Unknown
  3. Staff
    1. Yes
      1. Name
      2. Classes shared with case
    2. No
    3. Unknown

6. On most days, did you wear a mask when using shared spaces within your cohort?

  1. Always
  2. Sometimes
  3. Never
  4. Unknown

7. When interacting with members of your cohort, do the other students or staff typically wear a mask?

  1. Students
    1. Always
    2. Sometimes
    3. Never
    4. Unknown
  2. Teachers
    1. Always
    2. Sometimes
    3. Never
    4. Unknown
  3. Staff
    1. Always
    2. Sometimes
    3. Never
    4. Unknown

8. Within your cohort were there classes and/or activities during which it was difficult to consistently wear a mask?

  1. No difficulty
  2. Sometimes difficult
  3. Always difficult
  4. Unknown

9. In which situations did you find it difficult to wear a mask? (If there is more than 1 situation where you found it difficult to wear a mask, please list each class)

  1. Class
  2. Location
  3. Activity

10. Within your cohort were there classes and/or activities during which it was difficult to maintain physical distance of at least 2 metres?

  1. No difficulty
  2. Sometimes difficult
  3. Always difficult
  4. Unknown

11. In which situations did you find it difficult to maintain physical distance? (If there is more than 1 situation where you found it difficult to maintain physical distance, please list each class)

  1. Class
  2. Location
  3. Activity

12. Please provide any additional details and comments on cohort or classroom exposures:

Back to Appendix II: School-based COVID-19 outbreak investigation - complementary case questionnaire section 4

Supplement to section 6: Transportation exposure

Download and print Appendix II: Supplementary questionnaire to section 6: Transportation exposure in PDF or Word.

Section 6a: Private vehicle

Following are questions if you used a private vehicle in the 14 days prior to [Best Date].

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

Wherever possible please consider gathering information from the school related to transportation policies in advance of the interview, to help prompt the case/proxy while questioning.

1. Who was in the vehicle? (select all that apply)

  1. Parents/guardian
  2. Siblings
  3. Adult friend(s)
  4. Children Friend(s)
  5. Colleague
  6. Other:

2. Please provide the following information for all the people who were in the vehicle who were non-household members two days before [Best Date]:

  1. Name (e.g. Jane Doe)
  2. Seat in car relative to the case (e.g. beside the case in the back seat)

3. Do you have any additional information to share or comments?

Section 6b: School bus

Following are questions if you used a school bus in the 14 days prior to [Best Date].

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

Wherever possible please consider gathering information from the school related to transportation policies in advance of the interview, to help prompt the case/proxy while questioning

1. Are you able to describe the bus route or number, pickup location and time?

  1. Home to school
    1. Route (number and name)
    2. Row and seat number
    3. Pick up location
    4. Pick up time
  2. School to home
    1. Route (number and name)
    2. Row and seat number
    3. Pick up location
    4. Pick up time
  3. Other:
    1. Route (number and name)
    2. Row and seat number
    3. Pick up location
    4. Pick up time

2. Did you have an assigned seat on the bus?

  1. Yes
  2. No
  3. Unknown

3. In the 14 days prior to [Best Date], did your seating assignment change?

  1. Yes
  2. No
  3. Unknown

4. On most days was there someone sitting near you on the school bus? (i.e. sharing the same seat, within 2 rows in front or behind, within 2 seats next to their seat and diagonally front and behind)

  1. Yes
    1. Please provide the following information for all people who were sitting near you on the bus who were non-household members two days before [Best Date]
      1. Name (e.g. Jane Doe)
      2. Seat in bus relative to the case (e.g. Sitting in seat directly behind the case)
  2. No
  3. Unknown

5. Do you have any additional information to share or comments?

Section 6c: Public transportation

Following are questions if you used public transportation in the 14 days prior to [Best Date].

Applies to all cases. All questions refer to the 14 days prior to [Best Date].

Wherever possible please consider gathering information from the school related to transportation policies in advance of the interview, to help prompt the case/proxy while questioning.

  1. Describe the route and scheduled time that you took public transit (bus, trains, LRT). (i.e. Did you take the same routes every day? Which days were different? Do you usually sit in the same section of the vehicle every day?) (If you took different routes every day, please provide the following information for each day)
    1. Travel direction (i.e. home to school, school to home)
    2. Date(s)
    3. Route (number and name)
    4. Row and seat number
    5. Pick up location
    6. Pick up time
  2. Comments:

Back to Appendix II: School-based COVID-19 outbreak investigation - complementary case questionnaire section 6

Supplement to section 7: Extracurricular activity exposure

Please complete this if the case has indicated they take part in extracurricular and social activities affiliated with the school either on site or off site. On-line activities are out of scope.

Download and print Appendix II: Supplementary questionnaire to section 7: Extracurricular activity exposure in PDF or Word.

1. Please provide the following information for all in-person extracurricular activities in school or affiliated with school. Include before/after school care in this list.

  1. Activity (i.e. band, sports, chess club, etc.)
  2. Date(s)
  3. Location
  4. Cohort (indicate)
    • Same cohort as school
    • Different cohort as school
    • Outside students/staff

2. Did the child attend before/after school care within the school?

  1. Yes
    1. Please provide the following information:
      1. Program name
      2. Date(s)
      3. Locations
      4. Cohort (indicate):
        • Same cohort as school
        • Different cohort as school
        • Outside students/staff
    2. At before/after school care was there anyone with symptoms of COVID-19?
      • Yes
        1. Provide name
        2. Provide date last seen:
      • No
      • Unknown
      • n/a
    3. No
    4. Unknown

3. Did the child attend out of school care?

  1. Yes
    1. Please provide the following information:
      1. Program name
      2. Date(s)
      3. Locations
      4. Cohort (indicate):
        • Same cohort as school
        • Different cohort as school
        • Outside students/staff
    2. At out of school care, was there anyone with symptoms of COVID-19?
      • Yes
        1. Provide name
        2. Provide date last seen:
      • No
      • Unknown
      • n/a
    3. No
    4. Unknown

4. Outside of classes, shared spaces at school, meals, and extracurricular activities have you interacted socially with any students or staff members from your school (i.e. a birthday party, informal get together, going to the mall, etc.)

  1. Yes
    1. Provide the following information:
      1. Activity
      2. Date(s)
      3. Location(s)
      4. Names of contacts
      5. In school cohort?
    2. Did anyone from these activities show symptoms of COVID-19?
      1. Yes
        1. Provide name
        2. Provide date last seen:
      2. No
      3. Unknown
      4. n/a
    3. No
    4. Unknown
    5. n/a

5. Please provide any additional detail on any extracurricular activities / social gatherings related to school.

(i.e. Did people wear masks? Did people practice physical distancing? Was there shared food? Was there shared toys / equipment?)

Back to Appendix II: School-based COVID-19 outbreak investigation - complementary case questionnaire section 7

Appendix III: Social network analysis database structure

In order to set up the data for a social network analysis, two data sets are needed, likely requiring some data manipulation to set up. These data sets can then be used in a data visualization software to create a social network diagram. Multiple software options are available for visualizing social networks, including specialized social network analysis software such as Gephi or NetDraw. Many statistical software packages have social network analysis functionality, such as, the R epicontacts package.

1. A line list of cases/contact/events and their attributes (each row represents a node). An example of the line list set-up is shown in Figure 5 below:

Figure 5: Sample line list of individual nodes for social network analysis
Id A B C D
1 Node ID Node description Node type Node location
2 Node 1 Case1 Case Family1
3 Node 2 Case2 Case Family1
4 Node 3 Case3 Case Family1
5 Node 4 BBQ1 Event Family2
6 Node 5 Contact1 Contact Family2
7 Node 6 Contact2 Contact Family2

2. A line list of paired connections between nodes (each row represents an edge). An example of the line list of connections is shown in Figure 6 below:

Figure 5: Sample line list of individual nodes for social network analysis
Id A B
1 From To
2 Node1 Node2
3 Node1 Node3
4 Node1 Node4
5 Node2 Node3
6 Node2 Node4
7 Node3 Node4
8 Node4 Node5
9 Node4 Node6

Endnotes

Footnotes

Footnote 1

Government of Canada (2020). Canadian Field Epidemiology Program. [Available at : https://www.canada.ca/en/public-health/services/public-health-practice/canadian-field-epidemiology-program.html

Return to footnote 1 referrer

Footnote 2

Government of Canada (2020). Coronavirus disease (COVID-19): Summary of assumptions. [Available at : https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/health-professionals/assumptions.html#a2]

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Footnote 3

Government of Canada (2020). Coronavirus Disease (COVID-19) Case Report Form. [Available at :https://www.canada.ca/content/dam/phac-aspc/documents/services/diseases/2019-novel-coronavirus-infection/health-professionals/2019-nCoV-case-report-form-en.pdf]

Return to footnote 3 referrer

Footnote 4

WHO. Go.Data: Managing complex data in outbreaks [Available at: https://www.who.int/godata]

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Footnote 5

WHO. Introduction to Go.Data – Field data collection, chains of transmission and contact follow up. {Available at: https://openwho.org/courses/godata-en]

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Footnote 6

WHO (2020) Contact tracing in the context of COVID-19. Interim guidance. 10 May 2020 [Available at: https://www.who.int/publications/i/item/contact-tracing-in-the-context-of-covid-19]

Return to footnote 6 referrer

Footnote 7

Government of Canada (2020), Updated: Public health management of cases and contacts associated with COVID-19. Updated September 4, 2020 [Available at: https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/health-professionals/interim-guidance-cases-contacts.html]

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Footnote 8

Refer to local or provincial/territorial guidance on public health management of contacts.

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Footnote 9

Government of Canada (2020) COVID-19 guidance for schools Kindergarten to Grade 12. Updated September 17, 2020 [Available at: https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/health-professionals/guidance-schools-childcare-programs.html]

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Footnote 10

Government of Canada (2020) Understanding COVID-19 testing. Updated September 21, 2020. [Available at: https://www.canada.ca/en/public-health/services/publications/diseases-conditions/understanding-covid-19-testing.html

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Footnote 11

Refer to local or provincial/territorial guidance on public health management of contacts.

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Footnote 12

Park S, Kim Y, Yi S, et al. Coronavirus Disease Outbreak in Call Center, South Korea. Emerging Infectious Diseases. 2020;26(8):1666-1670. doi:10.3201/eid2608.201274.

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Footnote 13

Lu J, Gu J, Li K, et al. COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020. Emerging Infectious Diseases. 2020;26(7):1628-1631. doi:10.3201/eid2607.200764.

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Footnote 14

Dub T, Erra E, Hagberg L, et al. Transmission of SARS-CoV-2 following exposure in school settings: experience from two Helsinki area exposure incidents. medRxiv 2020.07.20.20156018; doi: https://doi.org/10.1101/2020.07.20.20156018

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Footnote 15

WHO (2020). The Unity Studies: WHO Early Investigations Protocols. [Available at: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/early-investigations]

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Footnote 16

Harvard T.H. Chan School of Public Health (2020. Schools for Health: COVID-19. [Available at: https://schools.forhealth.org/]

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Footnote 17

Government of Canada (2020). Canada Communicable Disease Report (CCDR). [Available at: https://www.canada.ca/en/public-health/services/reports-publications/canada-communicable-disease-report-ccdr.html]

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Footnote 18

World Health Organization (2020) Schools and other institutions transmission investigation protocol for coronavirus disease 2019 (COVID-19) version 1.1 30 September 2020 [Available at: https://apps.who.int/iris/bitstream/handle/10665/336253/WHO-2019-nCoV-Schools_transmission-2020.1-eng.pdf?sequence=1&isAllowed=y]

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