Adverse Events Following Immunization (AEFI) Quarterly Report for 2014 – Q1

Safety assessment summary for this Quarter:

• No vaccine safety concerns were identified in Quarter 1 for 2014.
• All serious cases were reviewed and found either to be expected based on known vaccine-related adverse reactions or to have alternate explanations such as commonly acquired infection (upper or lower respiratory tract infection by non-vaccine preventable pathogens like Respiratory Syncytial Virus (RSV) or the common cold virus) or exposures to other agents, such as antibiotics, that can also cause adverse events.
• As in previous years the vast majority (over 90%) of AEFIs reported in the quarter were neither serious nor unexpected

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 various activities related to vaccine safety assessment and monitoring including the federal government, provincial, territorial and local public health authorities, health care providers, vaccine industry and the public. The Public Health Agency of Canada (the Agency) conducts rigorous post-market safety surveillance through a national reporting system, the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS).

The primary purpose of vigilant vaccine safety surveillance is to detect vaccine safety concerns which include a possible increase in the severity or frequency of expected reactions or occurrence of one or more unexpected events (i.e. an event that is not consistent with Canadian product information or labelling) that need further investigation. This allows immunization providers and public health immunization program providers to take public health action at the level of the individual (e.g. further investigation to confirm a diagnosis and determine possible causes, consultation to rule out allergy to one or more vaccine components, or even a decision not to give subsequent doses of vaccine) and/or the immunization program (e.g. investigation of a cluster of adverse events, review of procedures to ensure that vaccine storage requirements have been strictly followed, or even a change in policy to adopt a less reactogenic vaccine).The Agency also shares adverse event following immunization (AEFI) data with Health Canada, the vaccine regulator in Canada, to enable regulatory action (such as issuing communications to immunization providers or the public regarding the concern, testing of a given lot of vaccine or requiring additional information or investigation by the vaccine distributor) related to vaccines marketed in Canada.

This is the first of what will be regular vaccine safety surveillance quarterly reports published by the Agency summarizing CAEFISS data. This report summarizes all reports of adverse events following immunization (AEFI) received by the Agency in 2014 from Jan 1^st to March 31^st (Quarter 1), regardless of the date the vaccine was actually given.

The current quarterly data for 2014 are compared to an average of all reports received during the same quarter (Jan 1^st to March 31^st) in several years prior. For this quarterly report, the comparison is to the last three years (2011, 2012, and 2013). The Agency will also provide cumulative data in subsequent quarters along with the appropriate historic comparisons. Thus, the final year-end quarterly report (Q4) this year will include data for all of 2014.

NOTES on INTERPRETATION: An 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 unfavorable or unintended sign, abnormal laboratory finding, symptom or disease". AEFI reports submitted to the Public Health Agency of Canada represent a suspicion, opinion or observation by the reporter as opposed to an assertion or proof that the vaccine may have caused the event. For most events a clear causal relationship is difficult to establish. Additional limitations to AEFI report data include varied reporting standards and underreporting, lack of certainty regarding the diagnostic validity of a reported event, missing information regarding other potential causes and other reporting biases. In short, this information should not be used to estimate the incidence of adverse events.

Results highlighted for Quarter 1 of 2014

Cumulative counts included in this Quarterly Report (Q1) include reports received from January 1^st to March 31^st 2014 and comparisons are made to the average number of reports received in the same quarter over the previous three calendar years (2011-2013). The reports analysed were extracted from the CAEFISS database on 29-April-2014 by the Public Health Agency of Canada (the Agency).

Figures 5 & 6: AEFIs reported by main reason and seriousness

Classification of AEFIs for Report Purposes: all AEFI reports are reviewed daily by health professionals to assign a main reason for reporting and the associated severity. The classification adheres closely to the national AEFI reporting form in order to provide meaningful feedback to public health authorities, health professionals and the public regarding the adverse event reporting profile. The main categories used when reporting an AEFI, and those reflected on the graph below, are defined as:

• Reactions at or near the vaccination site: most reported events involve inflammation at or near the site of vaccination. Further details can be found in section 9(a) of the reporting form.
• Allergic or allergic-like events: the most severe allergic event, anaphylaxis, is rare (≤1 episode per 100,000 doses administered) Further details can be found in section 9(b) of the reporting form.
• Neurologic events: seizures are the most commonly reported neurologic event especially in infants and toddlers who are prone to have seizures in association with fever. Such events are reported in Canada relatively frequently because they are actively sought and reported by the IMPACT network. Further details can be found in section 9(c) of the reporting form.
• Rash only: to be classified as 'rash only', the rash is the only sign or symptom reported. This would include hives that onset any time after immunization but are accompanied by no other signs or symptoms. Hives are a frequent occurrence in childhood and a cause is often not found
• Other events specified on the CAEFISS report form: this could include other events such as persistent crying (continuous or unaltered crying ≥ 3 hours, intussesception, hypotonic-hyporesponsive episodes (HHE), Further details can be found in section 9(d) of the reporting form.

Events not clearly falling into one of the categories listed above are classified into one of four additional categories:

• Systemic events: these are primarily events involving many body systems often accompanied by fever. Any recognized syndromes are classified as systemic events and include such illnesses as Kawasaki syndrome, Steven-Johnson syndrome, Henoch-Schonlein purpura, fibromyalgia and serum sickness. In addition evidence for infection of one or more body parts (respiratory infection, bladder infection, etc.) are included in this category as are instances of rash that is non-allergic in origin and is accompanied by other signs and symptoms such as fever, cough and conjunctivitis. General symptoms such as fatigue, malaise, lethargy, headache, myalgias including influenza-like illnesses are classified as systemic events. Finally fever as the only adverse event reported is included in this category.
• Vaccination anxiety related events: this includes fainting (syncope) with or without seizure-like movements which may briefly accompany a fainting episode. Other events included in this category are clusters of events often seen within minutes of immunization indicative of anxiety such as pallor, shakiness, feeling cold, hyperventilation, etc.
• Miscellaneous other events: all other adverse events that don't fit into any of the above categories are captured as miscellaneous events. These may be further categorized by the predominant body system they fall under such as gastrointestinal, cardiac, genitourinary, etc.
• Vaccination error without an associated AEFI: on occasion reports are submitted of an error in immunization without any associated adverse event. Examples include use of an expired product or incorrect administration of a product (e.g. giving a vaccine into the muscle when it should have been injected subcutaneously).