Adverse Events Following Immunization (AEFI) Quarter 1 Report for 2016 (January 1 – March 31)

Background

Vaccines are closely monitored in Canada at all phases of the vaccine product ‘life cycle’ from discovery through market authorization (pre-market) and beyond, as people begin using them (post-market). Many stakeholders are involved in vaccine safety assessment and monitoring including the federal government, provincial, territorial and local public health authorities, health care providers, vaccine industry and the public. Provincial and territorial immunization programs monitor AEFIs and report concerns to the Public Health Agency of Canada (the Agency) or through the Vaccine Vigilance Working Group (VVWG).  The Agency conducts post-market safety surveillance through a national reporting system, the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS).

An Adverse Event Following Immunization (AEFI) is defined as any untoward medical occurrence which follows immunization and which does not necessarily have a causal relationship with the usage of the vaccine. The adverse event may be any unfavourable or unintended sign, abnormal laboratory finding, symptom or disease. Serious AEFIs are those which are life-threatening, result in hospitalization or a prolongation of hospitalization, result in persistent or significant disability, or where the outcome is a birth defect or death, as defined by the World Health Organization (WHO). AEFIs not meeting the definition of a serious event are classified as non-serious.

WHO defines a vaccine safety signal as information (from one or multiple sources) that indicates a new and potentially causal association, or a new aspect of a known association, between a vaccine and an event previously unknown or incompletely documented that could affect health. Epidemiological studies are usually needed to assess the causal relationship between the vaccine and the signal. The primary purpose of vaccine post market surveillance is to detect safety concerns. These concerns include a possible increase in the severity or frequency of expected AEFIs, or occurrence of one or more unexpected events (i.e. an event that is not consistent with Canadian product information or labelling). This allows immunization providers and public health immunization program providers to take public health action at the level of the:

• individual (such as further investigations to confirm a diagnosis and determine possible causes, consultation to rule out allergy to one or more vaccine components, or evaluate whether or not to give subsequent doses of a vaccine), and/or
• immunization program (such as investigation of a cluster of adverse events, review of procedures to ensure that vaccine storage requirements have been strictly followed, or consideration of a change in policy to adopt a less reactogenic vaccine).

The Agency also shares AEFI data with Health Canada's Health Products and Foods Branch, the national regulatory authority for vaccines in Canada.  This enables formal action related to vaccines marketed in Canada to take place if needed. These actions may include issuing communications to immunization providers or the public regarding the safety concern or requiring additional information or investigation by the vaccine distributor, or changes to the product labeling.

Vaccine safety surveillance reports summarizing CAEFISS data are released by the Agency on a routine basis. The Quarterly Reports summarize all AEFI reports received by the Agency from January to March (Quarter 1), April to June (Quarter 2), July to September (Quarter 3) and October to December (Quarter 4), regardless of the date the vaccine was given.

In order to reflect variability in the AEFIs reported from year to year, each quarter's data are shown along with an average of the preceding four years' quarterly data; in other words, the data in this quarter, Quarter 1, are shown along with the average Quarter 1 data from the previous 4 years. However, because these data reflect reports received in the particular quarter, and not necessarily when the vaccine was given, they can be subject to variation depending on both when and how reports are received, processed and forwarded by provincial/territorial public health authorities as well as on the type of vaccine products used, distributed, and how many and which populations received them in a given quarter. Therefore, the ability to compare and interpret patterns in these data is limited. The report does provide a data snapshot that highlights serious and non-serious AEFI reports received for descriptive purposes.

Results Highlighted for Quarter 1 of 2016

Counts included in this Quarterly Report (Q1) include AEFI case reports routinely received from January 1, 2016 to March 31, 2016 and comparisons are made to the average number of reports received in the same quarter over the previous four calendar years (2012-2015). The reports analysed were extracted from the CAEFISS database on August 2, 2016 by the Agency.

All reports are coded with a main reason for reporting through a Medical Case Review (MCR) of individual case safety reports processed and coded using MedDRA, a standardized medical terminology that supports data entry, retrieval, evaluation and presentation of clinical information. Therefore, if more than one event is described, the one that is determined through MCR to have led to reporting is coded as the primary AEFI. In addition, all reports describing a serious event were reviewed and unless highlighted in this report, found either to be expected (based on known vaccine-related adverse reactions), to have alternate explanations not related to vaccination, or are currently being monitored or investigated further.

During Q1 of 2016, one jurisdiction sent data that had been omitted from routine transmission due to technical issues, representing 2,174 reports out of 2,814 received during this quarter. AEFIs reported were for vaccines administered between 2001 and 2016. These case reports, not included in the main text analysis, are summarized in the text box below:

Retrospective cases received during Q1:

• Total of 2,174 reports
• Vaccines administered between 2001 and 2016
• Proportion of serious reports: 4% (N=90)
• Mean age of cases: 20 years old (median: 9) at time of immunization.

Number of AEFI and Serious AEFI Reports

A total of 639 AEFI reports were submitted to the Agency in the first quarter of 2016 by ten provinces and one territory. During Q1 of 2012, 2013, 2014 and 2015, the Agency received an average of 890 (range: 739-1257) reports from ten provinces and two territories [Figure 1]. The lower number of reports can be explained in part by technical issues which resulted in a substantial decrease in reports from one jurisdiction starting in mid-2013.

A total of 52 AEFI reports received by the Agency in Q1 of 2016 were classified as serious (8% of all AEFI reports). During Q1 of 2012, 2013, 2014 and 2015, the Agency received an average of 62 (range: 54-67) serious AEFI reports (4% to 9% of all AEFI reports).

Frequency of Serious and Non-serious AEFI Reports by Age Group

Table 1 shows the number of serious and non-serious AEFI reports by age group in Q1 of 2016, compared to the 2012-2015 average. Fewer serious and non-serious reports were received in Q1 of 2016 compared to the 2012-2015 average. This could be explained in part by technical issues which prevented one jurisdiction from transmitting their data from mid-2013 to 2016.

AEFIs by Major Classification

Figure 2 presents the main types of AEFIs (both serious and non-serious) reported during Q1.

The main types of AEFI reported by level of seriousness for Q1 of 2016 compared to the 2012-2015 average is shown in Table 2. In Q1 of 2016 as well as in the past 4 years, reactions at or near the vaccination site, allergic or allergic-like events, and rash were the main AEFIs reported for non-serious cases; neurologic events (which are most often seizures triggered by fever) followed by systemic events (i.e., events involving many body systems often accompanied by fever), were the most frequent serious AEFIs.

Vaccines administered in AEFI Reports

Table 3 lists the most commonly administered vaccines among AEFI reports received for Quarter 1 of 2016. Influenza vaccines had the most serious and non-serious AEFI reports consistent with the high volume of vaccines administered each year. Most vaccines had fewer serious reports compared to the 2012-15 average, except for Influenza and the DTaP booster; most vaccines had fewer non-serious reports compared to the 2012-15 average, except the Zoster virus vaccine which was introduced in Canada in 2008 and became much more widely distributed between 2012 to 2015. As mentioned previously, lower reporting frequency in the current quarter relative to the same period in previous years could be explained in part by technical issues which continue to prevent one jurisdiction from transmitting their data from mid-2013 to 2016.

Summary

This Quarter 1 report for 2016 is based on reports of adverse events received at the Agency from provincial/territorial public health authorities and active, pediatric hospital based surveillance. Detailed evaluation of the reports and reporting patterns in collaboration with provincial/territorial vaccine safety focal points of the VVWG and Health Canada have not identified any vaccine safety signals of concern. The tables and figures in this report provide a snapshot of the data reviewed and provide an overview of adverse event reporting in Canada.