Events supposedly attributable to vaccination or immunization during pandemic influenza A (H1N1) vaccination campaigns in Latin America and the Caribbean

Abstract

As part of the vaccination activities against influenza A[H1N1]pdm vaccine in 2009-2010, countries in Latin American and the Caribbean (LAC) implemented surveillance of events supposedly attributable to vaccines and immunization (ESAVI). We describe the serious ESAVI reported in LAC in order to further document the safety profile of this vaccine and highlight lessons learned. We reviewed data from serious H1N1 ESAVI cases from LAC countries reported to the Pan American Health Organization/World Health Organization. We estimated serious ESAVI rates by age and target group, as well as by clinical diagnosis, and completed descriptive analyses of final outcomes and classifications given in country. A total of 1000 serious ESAVI were reported by 18 of the 29 LAC countries that vaccinated against A[H1N1]pdm. The overall reporting rate in LAC was 6.91 serious ESAVI per million doses, with country reporting rates ranging from 0.77 to 64.68 per million doses. Rates were higher among pregnant women (16.25 per million doses) when compared to health care workers (13.54 per million doses) and individuals with chronic disease (4.03 per million doses). The top three most frequent diagnoses were febrile seizures (12.0%), Guillain-Barré Syndrome (10.5%) and acute pneumonia (8.0%). Almost half (49.1%) of the serious ESAVI were reported among children aged <18 years of age; within this group, the highest proportion of cases was reported among those aged <2 years (53.1%). Of all serious ESAVI reported, 37.8% were classified as coincidental, 35.3% as related to vaccine components, 26.4% as non-conclusive and 0.5% as a programmatic error. This regional overview of A[H1N1]pdm vaccine safety data in LAC estimated the rate of serious ESAVI at lower levels than other studies. However, the ESAVI diagnosis distribution is comparable to the published literature. Lessons learned can be applied in the response to future pandemics.

International Consensus (ICON): allergic reactions to vaccines

“…Similarly, a review of reported adverse events following immunization for pandemic monovalent H1N1 vaccine in Latin American and the Caribbean in the 2009–2010 season reported anaphylaxis as 7.6 % of the 1000 events supposedly attributable to vaccines and immunizations, representing a rate of 0.53 cases per million doses (0.41–0.64, 95 % CI). Of these, 45/76 cases occurred in age group 18–59 years, and 14 occurred in those under age 2 years [ 63 ] (D).…”

Contributions and challenges for worldwide vaccine safety: The Global Advisory Committee on Vaccine Safety at 15 years

“…GACVS is also perceived as a valued mechanism by the member states for providing timely independent evidence-based reviews and conclusions on current, emerging or foreseeable vaccine safety issues for policy makers, immunization program managers and technical advisory committees. With many more vaccines becoming available and enhanced AEFI surveillance systems are detecting vaccine safety signals more frequently worldwide [50,51]. Safety concerns are a well-recognized, albeit only one of many, contributing factors to increasing vaccine hesitancy noted in some communities [52–54].…”

Relief After COVID-19 Vaccination: A Doubtful or Evident Outcome?

“…Anxiety-related events that occur soon after COVID-19 vaccination may cause concern among other vaccine recipients and staff members, particularly in a mass vaccination scenario ( 10 ). When adverse events were reported related to the 2009 H1N1 influenza pandemic vaccine, some countries did not provide timely information about the association of the events with the vaccine, causing lack of confidence in the vaccine that subsequently influenced vaccine uptake and communication ( 11 , 12 ). Thus, sustaining trust during a pandemic is critical for health authorities, both if repeated vaccinations are necessary and in preparation for future health emergencies ( 13 ).…”