Canadian Adverse Events Following Immunization Surveillance System (CAEFISS): Annual report for vaccines administered in 2012

Revaccination outcomes among adolescents and adults with suspected hypersensitivity reactions following COVID-19 vaccination: A Canadian immunization research network study

BACKGROUND

COVID-19 vaccination has been associated with anaphylaxis and hypersensitivity reactions. Infectious disease physicians and allergists in the Canadian Special Immunization Clinic (SIC) Network developed guidance for evaluating patients with adverse events following immunization (AEFI) including suspected hypersensitivity. This study evaluated management and adverse event recurrence following subsequent COVID-19 vaccinations.

METHODS

Individuals aged 12 years and older enrolled at participating SICs before February 28, 2023 who were referred for suspected or diagnosed hypersensitivity reaction following COVID-19 vaccination, or for prevaccination assessment of suspected allergy to a COVID-19 vaccine component were included. De-identified clinical assessments and revaccination data, captured in a centralized database, were analyzed. The Brighton Collaboration case definition (BCCD) for anaphylaxis (2023 version) was applied.

RESULTS

The analysis included 206 participants from 13 sites: 26 participants referred for pre-vaccination assessment and 180 participants referred for adverse events following COVID-19 vaccination (15/180 [8.3%] with BCCD confirmed anaphylaxis, 84 [46.7%] with immediate hypersensitivity symptoms not meeting BCCD, 33 [18.3%] with other diagnosed hypersensitivity reactions, and 48 [26.7%] participants with a final diagnosis of non-hypersensitivity AEFI). Among participants referred for AEFIs following COVID-19 vaccination, 166/180 (92.2%) were recommended for COVID-19 revaccination after risk assessment, of whom 158/166 (95.2%) were revaccinated (all with a COVID-19 mRNA vaccine). After revaccination, 1/15 (6.7%) participants with prior anaphylaxis, 1/77 (1.3%) with immediate hypersensitivity not meeting criteria for anaphylaxis and 1/24 (4.2%) with other physician diagnosed hypersensitivity developed recurrent AEFI symptoms that met the BCCD for anaphylaxis. All 26 participants referred pre-vaccination, including 9 (34.6%) with history of polyethylene glycol-asparaginase reactions, were vaccinated without occurrence of immediate hypersensitivity symptoms.

CONCLUSIONS

Most individuals in this national cohort who experienced a hypersensitivity event following COVID-19 vaccination and were referred for specialist review were revaccinated without AEFI recurrence, suggesting that specialist evaluation can facilitate safe revaccination.

National safety monitoring of vaccines from the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS), 2018-2019

Background

The Canadian Adverse Events Following Immunization Surveillance System (CAEFISS) is a comprehensive vaccine safety surveillance system that includes both passive and active surveillance of vaccines administered in Canada. This work presents a summary of adverse events following immunization (AEFI) nationally for 2018 and 2019.

Methods

Data extracted from CAEFISS included all AEFI reports received by the Public Health Agency of Canada by April 30, 2022, for vaccines marketed in Canada and administered between January 1, 2018, and December 31, 2019. Descriptive statistics were conducted on AEFI reports by type of surveillance program (i.e., active vs. passive), AEFIs, demographics, healthcare utilization, outcome, seriousness of adverse events and type of vaccine.

Results

Between 2018 and 2019, 5,875 AEFI reports were received from across Canada. The average annual AEFI reporting rate was 10.9/100,000 doses distributed in Canada for vaccines administered during 2018-2019 and was found to be inversely proportional to age. The majority of reports (91%) were non-serious events, involving vaccination site reactions, rash and allergic events. Overall, there were 511 serious adverse event reports during 2018-2019. Of the serious adverse event reports, the most common primary AEFIs were anaphylaxis followed by seizure. There were no unexpected vaccine safety issues identified or increases in frequency or severity of adverse events.

Conclusion

Canada's continuous monitoring of the safety of marketed vaccines during 2018-2019 did not identify any increase in the frequency or severity of AEFIs, previously unknown AEFIs, or areas that required further investigation or research.

Canadian vaccine safety surveillance reports following immunization with seasonal influenza vaccines, 2021-2022

Background

Seasonal influenza vaccines (SIV) authorized for use in Canada have all undergone rigorous regulatory assessments for safety and effectiveness. Serious adverse events following immunization (AEFI) can occur, though they are rare. Continuous safety surveillance of vaccines during the post-marketing phase is a critical component of vaccination programs. This enables the detection of rare, late onset, or unexpected adverse events. An updated safety summary following the introduction of any new vaccines and/or formulations to immunization programs is necessary for refining the risk-benefit profile of a specific vaccine and maintaining public confidence. Here we provide an updated safety summary for SIVs distributed during the 2021/2022 influenza season from AEFI reports submitted to the Canadian Adverse Event Following Immunization Surveillance System (CAEFISS) and the Canadian Vigilance Database (CVD).

Methods

We searched CAEFISS and CVD for individuals who were vaccinated with a SIV between October 1, 2021, and March 31, 2022. Descriptive statistics were calculated, including median age of vaccinated individuals, vaccines co-administered with SIV, and the most frequently reported AEFIs. Crude AEFI reporting rates were calculated by severity of the AEFI report, and SIV-type using doses distributed data. Medical reviews were conducted for reports including death, serious events (or outcomes) after SIV were administered alone, and selected adverse events (i.e., anaphylaxis, Guillain-Barré syndrome, febrile seizures, oculo-respiratory syndrome). Disproportionality analysis was used to identify potential safety signals among SIV and AEFI pairs.

Results

There were 448 AEFI reports, with most AEFI classified as non-serious events (84.2%). The majority of reports described vaccination in adults at least 65 years of age (38.6%). The most frequently reported AEFIs were vaccination site pain, urticaria, pyrexia and rash. Medical review of AEFI reports did not find any evidence that reported deaths were related to vaccination with SIV. Among serious reports, nervous system disorders were the most commonly reported medical conditions. A higher number of events related to vaccination errors were also identified using disproportionality analysis.

Conclusion

Findings from our analysis of reports to CAEFISS and CVD following vaccination with SIV are consistent with the known safety profile of SIVs distributed during the 2021/2022 influenza season. The majority of reports were non-serious with the most common AEFI symptoms occurring at the vaccination site or systemic symptoms that were self-limiting. The majority of vaccination error reports involved the administration of the vaccine at an inappropriate site, although no serious AEFIs were reported.

Factors associated with intention for revaccination among patients with adverse events following immunization

OBJECTIVES

Individuals and healthcare providers may be uncertain about the safety of revaccination after an adverse event following immunization (AEFI). We identified factors associated with physician recommendation for revaccination and participant intention to be revaccinated among patients with adverse events following immunization (AEFIs) assessed in the Canadian Special Immunization Clinic (SIC) Network from 2013 to 2019.

METHODS

This prospective observational study included patients assessed in the Canadian Special Immunization Clinic Network from 2013 to 2019 for an AEFI who required additional doses of the vaccine temporally associated with their AEFI. Participants underwent standardized assessment and data collection. Physician recommendations regarding revaccination and participant intent for revaccination were recorded. AEFI impact on daily activities and need for medical attention was captured as low, moderate, high impact and serious (e.g., requiring hospitalization). Multivariable logistic regression analysis identified factors associated with physician recommendation and participant intention for revaccination, controlling for province of assessment.

RESULTS

Physician recommendation was significantly associated with the type of AEFI and AEFI impact. Compared to large local reaction, physician recommendation for revaccination was reduced for immediate hypersensitivity (aOR: 0.24 [95% CI: 0.08-0.76]) and new onset autoimmune disease (aOR: 0.16; 95% CI: 0.04-0.69). Compared to low impact AEFIs, physician recommendation was reduced for moderate (aOR: 0.22 [95% CI: 0.07-0.65]), high impact (aOR: 0.08 [95% CI: 0.02-0.30]), and serious AEFIs (aOR: 0.11 [95% CI: 0.03-0.37]). Participant intention for revaccination was significantly associated with AEFI impact, with reduced odds for high versus low impact AEFIs (aOR: 0.12 [95% CI: 0.04-0.42]).

CONCLUSION

Physicians appear to use AEFI type and impact to guide recommendations while patients use primarily AEFI impact to form intentions for revaccination. The findings may help inform counselling for patients with AEFIs.

Revaccination and Adverse Event Recurrence in Patients with Adverse Events following Immunization

OBJECTIVES

To estimate the risk of recurrence of adverse events following immunization (AEFIs) upon revaccination and to determine among patients with suspected vaccine allergy whether allergy skin test positivity was associated with AEFI recurrence.

STUDY DESIGN

This prospective observational study included patients assessed in the Canadian Special Immunization Clinic Network from 2013 to 2019 with AEFIs who required revaccination with the vaccine temporally associated with their AEFI. Participants underwent standardized assessment and data collection. Special Immunization Clinic physicians used guidelines to inform their recommendations. Participants were followed up after revaccination to capture AEFI recurrences. Data were transferred to a central database for descriptive analysis.

RESULTS

Overall, 588 participants were assessed for 627 AEFIs; 570 (91%) AEFIs occurred in children <18 years of age. AEFIs included immediate hypersensitivity (130/627; 21%), large local reactions (110/627; 18%), nonurticarial rash (51/627; 8%), seizures (26/627; 4%), and thrombocytopenia (11/627; 2%). Revaccination was recommended to 513 of 588 (87%) participants. Among participants recommended and due for revaccination during the study period, 63% (299/477) were revaccinated. AEFI recurrence was 10% (31/299) overall, 31% (15/49) for large local reactions, and 7% (5/66) for immediate hypersensitivity. No recurrence was serious. Among 92 participants with suspected vaccine allergy who underwent skin testing and were revaccinated, the negative predictive value of skin testing for AEFI recurrence was 96% (95% CI 92.5%-99.5%).

CONCLUSIONS

Most individuals with AEFIs were safely revaccinated. Among those with suspected vaccine allergy, skin testing may help determine the safety of revaccination.

Interpretation of vaccine associated neurological adverse events: a methodological and historical review

As a result of significant recent scientific investment, the range of vaccines available for COVID-19 prevention continues to expand and uptake is increasing globally. Although initial trial safety data have been generally reassuring, a number of adverse events, including vaccine induced thrombosis and thrombocytopenia (VITT), have come to light which have the potential to undermine the success of the vaccination program. However, it can be difficult to interpret available data and put these into context and to communicate this effectively. In this review, we discuss contemporary methodologies employed to investigate possible associations between vaccination and adverse neurological outcomes and why determining causality can be challenging. We demonstrate these issues by discussing relevant historical exemplars and explore the relevance for the current pandemic and vaccination program. We also discuss challenges in understanding and communicating such risks to clinicians and the general population within the context of the 'infodemic' facilitated by the Internet and other media.

Assessing safety of Ontario’s publicly funded MMR and MMRV immunization programs, 2012 to 2016

Background

The combined measles, mumps, rubella (MMR) and measles, mumps, rubella, and varicella (MMRV) vaccines are part of Ontario’s routine immunization schedule.

Objective

To assess adverse events following immunization (AEFIs) reported in Ontario following administration of MMR and MMRV vaccines between 2012 and 2016.

Methods

Reports of AEFIs were extracted from the provincial surveillance database on May 9, 2017. Events were grouped by provincial surveillance definitions. Reporting rates were calculated using provincial population estimates or net doses distributed as the denominator. A serious AEFI is defined as an AEFI that resulted in an in-patient hospitalization or death.

Results

Overall, 289 AEFIs were reported following administration of MMR (n=246) or MMRV (n=43) vaccines, for annualized reporting rates of 16.6 and 8.8 reports per 100,000 distributed doses, respectively. The highest age-specific reporting rate was in children aged 1 to 3 years for MMR (7.7 per 100,000 population) and children aged 4 to 9 years for MMRV (0.8 per 100,000 population). Systemic reactions were the most frequently reported event category, while rash was the most frequently reported event for both vaccines. There were 22 serious AEFIs, 19 following MMR and 3 following MMRV (1.3 and 0.6 per 100,000 doses distributed, respectively).

Conclusions

Our assessment found a low reporting rate of adverse events following MMR and MMRV vaccines in Ontario. No safety concerns were identified. Our findings are consistent with the safety profiles of these vaccines. Continued monitoring of vaccine safety is necessary to maintain timely detection of unusual postvaccine events and public confidence in vaccine safety.

Retrospective study of immunization errors reported in an online Information System

Objective:

to analyze the immunization errors reported in an online Information System.

Method:

retrospective study conducted with data from the Adverse Event Following Immunization Surveillance Information System. Immunization errors were analyzed with respect to demographic characteristics and the vaccination process. Frequencies and error incidence rates have been calculated. Binomial and chi-square tests were used to verify differences in the proportions of the variables.

Results:

501 errors were analyzed, the majority involving routine doses (92.6%), without Adverse Event Following Immunization (90.6%) and in children under five years old (55.7%). The most frequent types of errors were inadequacy in the indication of the immunobiological (26.9%), inadequate interval between doses (18.2%) and error in the administration technique (14.2%). The overall error incidence rate was 4.05/100,000 doses applied; the highest incidences of routine vaccines were for human rabies vaccine, human papillomavirus and triple viral; the incidence rate of errors with Adverse Events Following Immunization was 0.45/100,000 doses applied.

Conclusion:

it was found that immunization errors are a reality to be faced by the health systems, but they are amenable to prevention through interventions such as the adoption of protocols, checklists and permanent education in health.

Trends of Adverse Events Following Immunization (AEFI) Reports of Human Papillomavirus Vaccine in the Valencian Community—Spain (2008–2018)

Vaccine safety surveillance is essential in vaccination programs. We accomplished a descriptive study of surveillance AEFI-reporting rate in human papillomavirus (HPV) vaccine administered in the Valencian Community, Spain. Data were obtained from Spanish Pharmacovigilance Adverse Reactions Data (FEDRA). Reporting rates were calculated using local net doses distributed as the denominator. Trends were assessed using joinpoint regression with annual percent change (APC) reported. The AEFI-reports decreased between 2008 and 2018 in two periods, a fast decreasing rate from 2009 to 2011 (from 192.2 to 24.93 per 100000 doses; APC, −54.9%; 95%CI [−75.2; −17.7]), followed by a stable trend (−13% APC, 95%CI [−26.1; 2.4]). For the age group analysis, only the group aged 14–15 years old followed the same trend with -58.4% (95%CI [−73.9; −33.8]) APC during 2008–2011, and −8.8% (95%CI [−27.7; 15]) APC during 2011-2018. The majority of the reports (73.82%) were nonserious, involving reactions at or near the vaccination site, headache, and dizziness events. No death was reported. AEFI-reporting rates for HPV immunization in the Valencian Community have decreased considerably with two trend periods observed for girls aged 14–15 years old. Currently, the AEFI reporting rate shows a decreasing trend, perhaps following the Weber effect, and it could also be affected by media attention and coverage.

Vaccine safety surveillance in Canada: Reports to CAEFISS, 2013-2016

BACKGROUND

Canada has one of the strongest vaccine safety surveillance systems in the world. This system includes both passive surveillance of all vaccines administered and active surveillance of all childhood vaccines.

OBJECTIVES

To provide 1) a descriptive analysis of the adverse events following immunization (AEFI) reports for vaccines administered in Canada, 2) an analysis of serious adverse events (SAEs) and 3) a list of the top ten groups of vaccines with the highest reporting rates.

METHODS

Descriptive analyses were conducted of AEFI reports received by the Public Health Agency of Canada (PHAC) by August 14, 2017, for vaccines marketed in Canada and administered from January 1, 2013 to December 31, 2016. Data elements in this analysis include: type of surveillance program, AEFIs, demographics, health care utilization, outcome, seriousness of adverse events and type of vaccine.

RESULTS

Over the four year period, 11,079 AEFI reports were received from across Canada. The average annual AEFI reporting rate was 13.4/100,000 doses distributed in Canada for vaccines administered during 2013-2016 and was found to be inversely proportional to age. The majority of reports (92%) were non-serious events, involving vaccination site reactions rash and allergic events. Overall, there were 892 SAE reports, for a reporting rate of 1.1/100,000 doses distributed during 2013-2016. Of the SAE reports, the most common primary AEFIs were anaphylaxis followed by seizure. Meningococcal serogroup C conjugate vaccines (given concomitantly) were responsible for the highest rates of AEFIs, at 91.6 per 100,000 doses distributed. There were no unexpected vaccine safety issues identified or increases in frequency or severity of expected adverse events.

CONCLUSION

Canada's continuous monitoring of the safety of marketed vaccines during 2013-2016 did not identify any increase in the frequency or severity of AEFIs, previously unknown AEFIs, or areas that required further investigation or research. Vaccines marketed in Canada continue to have an excellent safety profile.

Did the New Italian Law on Mandatory Vaccines Affect Adverse Event Following Immunization's Reporting? A Pharmacovigilance Study in Southern Italy

Despite the well-recognized role of vaccines, coverage is far from optimal especially in children, representing a growing concern also in Italy. In order to reverse this emergency, the Italian Ministry approved in July 2017 the Law 119/2017, which renders mandatory and free of charge 10 vaccinations for patients aged 0–16. We aim to investigate the effects of the new Law 119/2017 on the reporting of adverse events following immunization related to mandatory vaccines into the Italian Pharmacovigilance database (Rete Nazionale di Farmacovigilanza – RNF). Therefore, we analyzed the spontaneous reports of suspected adverse events following immunization recorded in Campania Region (South of Italy) from December 1, 2016, to March 31, 2018. During the study period, 69 reports, covering 179 AEFIs, related to mandatory vaccines were sent to Campania Pharmacovigilance Regional Center. A substantial increase in AEFIs reporting was observed after the adoption of Law 119/2017. Out of 69 reports, 62% reported AEFIs that were considered as not serious and 78% had a favorable outcome. Out of 179 AEFIs, more than half referred to the following SOC: “general disorders and administration site conditions,” “nervous system disorders,” and “psychiatric disorders.” The highest number of reports came from patient/citizen. After the adoption of the Law 119/2017, there was an increase in the number of reports (18 before the adoption of the Law vs. 51 after). According to reported AEFIs during the entire period, no worrying safety data have emerged. In our opinion, the increase in the number of AEFIs’ reports should be related to the increase in vaccination coverage as well as to the intense debate that has followed the new Law. In this context, the continuous monitoring of vaccine safety and the fully implementation of vaccine–vigilance programs play a key role in achieving higher confidence in immunization programs and optimal vaccination coverage rate.

Application of the revised WHO causality assessment protocol for adverse events following immunization in India

BACKGROUND

In 2013, the World Health Organization (WHO) and CIOMS introduced a revised Causality Assessment Protocol (CAP) for Adverse Events following Immunization (AEFI). India is one of the first countries to adopt the revised CAP. This study describes the application of the revised CAP in India.

METHODS

We describe use of CAP by India's AEFI surveillance program to assess reported AEFIs. Using publicly available results of causality assessment for reported AEFIs, we describe the results by demographic characteristics and review the trends for the results of the causality assessment.

RESULTS

A total of 771 reports of AEFI between January 2012 and January 2015, completed causality review by August 2016. The cases were reported as belonging to a cluster (54%; n=302), hospitalized or requiring hospitalization (41%; n=270), death (25%; n=195), or resulting in disability (0.4%; n=3). The most common combinations of vaccines leading to report of an AEFI were DTwP, Hepatitis B, and OPV (14%; n=106), followed by Pentavalent and OPV (13%; n=103), and JE vaccine (13%; n=101). Using the WHO Algorithm, most AEFI reports (89%, n=683) were classifiable. Classifiable AEFI reports included those with a consistent causal association (53%; n=407), an inconsistent causal association (29%; n=226) or were indeterminate causal association with implicated vaccine(s) or vaccination process (6.5%; n=50) (Fig. 1); 88 reports remained unclassifiable.

CONCLUSIONS

The revised CAP was informative and useful in classifying most of the reviewed AEFIs in India. Unclassifiable reports could be minimized with more complete information from health records. Improvements in causality assessment, and standardization in reporting between countries, can improve public confidence in vaccine system performance and identify important vaccine safety signals.

Assessing vaccine safety within Ontario's Universal Influenza Immunization Program, 2012-2013 to 2014-2015

Background

Influenza vaccine is recommended to prevent influenza-related morbidity and mortality. Post-marketing surveillance of adverse events following influenza vaccine is essential to monitor vaccine safety, inform immunization program planning and evaluation, and build confidence in immunization.

Objective

To summarize adverse events following immunization (AEFIs) reported after receipt of influenza vaccines administered within the Universal Influenza Immunization Program in Ontario.

Methods

AEFIs following administration of influenza vaccines between September 1, 2012 and August 31, 2015 were extracted from the Integrated Public Health Information System (iPHIS) on September 1, 2015. Events were grouped by provincial surveillance definitions. Reporting rates were calculated using provincial population estimates or net doses distributed as the denominator. The standard World Health Organization definition of serious AEFIs was used.

Results

There were 12.1 million doses of influenza vaccine distributed in Ontario and 528 AEFIs reported following influenza vaccines administered over three seasons. The annualized reporting rate was 4.4 per 100,000 doses distributed with a significant decreasing trend over time (p<0.05). The median age was 39.6 years (range six months-96 years); children under four years of age had the highest reporting rate (3.5 per 100,000 population). Disproportionate reporting among females was observed (76.5 percent), most notably in those 18 years and older. The most frequently reported events were injection site reactions (36.2 percent of reports). Others included allergic skin reactions (21.1 percent) and rashes (17.3 percent). Serious AEFIs were rare with a reporting rate of 1.6 per million doses distributed.

Conclusion

This assessment found a low rate of reported adverse events following influenza vaccines administered in Ontario. Most reported events were mild and resolved completely. The findings were consistent with the very good safety profile of influenza vaccines.

An evaluation of the feasibility and usability of a proof of concept mobile app for adverse event reporting post influenza vaccination

The Canadian National Vaccine Safety network (CANVAS) gathers and analyzes safety data on individuals receiving the influenza vaccine during the early stages of annual influenza vaccination campaigns with data collected via participant surveys through the Internet. We sought to examine whether it was feasible to use a mobile application (app) to facilitate AEFI reporting for the CANVAS network. To explore this, we developed a novel smartphone app, recruited participants from a hospital influenza immunization clinic and by word of mouth and instructed them to download and utilize the app. The app reminded participants to complete the CANVAS AEFI surveillance surveys ("AEFI surveys") on day 8 and 30, a survey capturing app usability metrics at day 30 ("usability survey") and provided a mechanism to report AEFI events spontaneously throughout the whole study period. All survey results and spontaneous reports were recorded on a privacy compliant, cloud server. A software plug-in, Lookback, was used to record the on-screen experience of the app sessions. Of the 76 participants who consented to participate, 48(63%) successfully downloaded the app and created a profile. In total, 38 unique participants completed all of the required surveillance surveys; transmitting 1104 data points (survey question responses and spontaneous reports) from 83 completed surveys, including 21 usability surveys and one spontaneous report. In total, we received information on new or worsening health conditions after receiving the influenza vaccine from 11(28%) participants. Of the usability survey responses, 86% agreed or strongly agreed that they would prefer to use a mobile app based reporting system instead of a web-based system. The single spontaneous report received was from a participant who had also reported using the Day 8 survey. Of Lookback observable sessions, an accurate transmission proportion of 100% (n=290) was reported for data points. We demonstrated that a mobile app can be used for AEFI reporting, although download and survey completion proportions suggest potential barriers to adoption. Future studies should examine implementation of mobile reporting in a broader audience and impact on the quality of reporting of adverse events following immunization.

A spot of bother: Why varicella vaccine programs matter

Objective

To evaluate Ontario's provincial varicella vaccination program through analysis of aggregate varicella cases in order to determine whether there has been a decrease in reportable disease burden; and to assess varicella vaccine adverse events following immunization (AEFIs).

Methods

Aggregate varicella cases (1993-2013) were extracted from the reportable disease databases. Pre-program (1993-2004) and post-program (2007-2013) periods were chosen according to implementation of the publicly funded vaccination program. AEFIs following administration of varicella vaccines (2010-2013) were also extracted. Reporting rates were calculated using net doses distributed as the denominator. Serious AEFIs were defined using World Health Organization standards.

Results

The incidence of aggregate varicella reports decreased significantly over the study period (from 311.4 to 22.2 cases per 100,000 population in 1993 and 2013, respectively). Incidence also decreased significantly in all age groups between the pre- and the post-program periods with a shift in age distribution towards older individuals in the post-program period. A total of 162 AEFIs following varicella vaccine were reported between 2010 and 2013 for an annualized reporting rate of 14.6 per 100,000 doses distributed. The most common events were rash (37.3%), including eight reports of varicella-like rash (0.7 per 100,000 doses distributed). Ten serious events were reported (0.9 per 100,000 doses distributed), and all vaccine recipients recovered.

Conclusion

Significant reductions in varicella disease incidence and low AEFI reporting rates were observed with the introduction of the publicly funded varicella vaccine program in Ontario. Continued surveillance is indicated to further assess trends in varicella disease and vaccine safety.

Vaccine vigilance in Canada: Is it as robust as it could be?

Canada has been known to have one of the better vaccine safety surveillance capacities in the world, but in the early 2000s, it was noted there was still room for improvement. How has Canada done over the last decade and is there more to be done? Canada has done well. First, there has been significant progress made by the Vaccine Vigilance Working Group to enhance the passive vaccine safety monitoring system and address potential issues arising from the review of surveillance data and cases or clusters of concern. Second, there has been an increased investigative capacity for clusters of adverse events and other vaccine safety issues, including an assessment and referral system for individuals with adverse events following immunizations (AEFIs). Third, the use of the Brighton Collaboration definitions and other international standards has facilitated international collaboration and represents the best standard of practice. Despite all these improvements, however, there is more that could be done. The sensitivity of Canada's passive surveillance system still varies from one province and territory to another. The timeliness of the data exchange flow could improve. The AEFI Signal Response Protocol, which identifies the processes and required actions for timely management of any newly detected or emerging vaccine safety signals, is a critical piece of a robust vaccine safety system but it is still in the making. It is commendable that Canada has decided to expand its focus on evaluation research from influenza vaccines to vaccine-preventable diseases more broadly, with the establishment of the Canadian Immunization Research Network (CIRN). CIRN's newly developed Provincial Collaborative Network and the move toward record linkages is excellent. These new investments are welcome in light of the rich vaccine development pipeline, the increased pool of available vaccines, and the growing set of technologies for vaccines production, delivery, and safety monitoring. What would round this all out would be a stronger capacity to monitor the implementation of vaccination programs and vaccine coverage, and better documentation of the reduction of the disease burden attributable to vaccination programs. Canada's investment in vaccines for the health of all deserves no less.