Article Impact Level: HIGH Data Quality: STRONG Summary of JAMA Network Open, 5(6), e2218505. https://doi.org/10.1001/jamanetworkopen.2022.18505 Dr. Sarah Buchan et al
Points
- A population-based cohort study to assess the risk of myocarditis or pericarditis associated with COVID-19 mRNA vaccination
- Higher rates of these events following administration of mRNA-1273 as the second vaccine dose
- Higher rates of pericarditis or myocarditis are also observed among the male population and shorter interdose intervals
Summary
Multiple countries have observed an association between myocarditis or pericarditis and COVID-19 mRNA vaccines, including BNT162b2 or Pfizer-BioNTech Comirnaty and mRNA-1273 or Moderna Spikevax. Ontario, Canada, increased vaccine-safety surveillance in early June 2021. The enhanced surveillance occurred alongside changes in Ontario’s vaccination program such as eligibility expansion of vaccine recipients, heterologous vaccine schedules, an increase in the administration of the second dose, and the establishment of interdose intervals.
The population-based cohort study was designed to assess the rates of myocarditis or pericarditis occurring after mRNA vaccination by vaccine product, interdose interval, age, sex, heterologous or homologous schedule of vaccines, and dose number. The time duration for the study was December 2020-September 2021, during which the data was obtained from the passive vaccine-safety surveillance program and the COVID-19 vaccine registry in Ontario.
A total of 19,740,741 mRNA vaccine doses were administered from December 14, 2020, to September 4, 2021, in the Canadian province. In the provincial system of adverse events, 417 myocarditis or pericarditis cases were reported following COVID-19 mRNA vaccination. Further evaluation revealed that 297 of the cases fulfilled the inclusion criteria, which were based on levels 1-3 of Brighton Collaboration (BC) case definitions. The median age of these individuals was 24 years (age range 12-81 years). Among these individuals, 107 reported myopericarditis, 105 reported myocarditis, and 85 reported pericarditis. 87, 33, and 90 individuals were hospitalized for myocarditis, pericarditis, and myopericarditis respectively. The median time of onset of symptoms was reported to be 3 days after receiving the vaccine. Concerning the onset of myocarditis or pericarditis after the second dose, 179 and 200 cases occurred within 7 and 30 days respectively. Moreover, more than half of the cases occurred after the second dose, particularly with the mRNA-1273 vaccine. Males were predominantly involved, corresponding to 228 of the total cases. The rates of pericarditis or myocarditis were significantly higher in association with shorter interdose intervals.
The study suggests that longer interdose intervals and age-product-based considerations may lower the risk of adverse events following vaccination.
Link to the article: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2793551
References Buchan, S. A., Seo, C. Y., Johnson, C., Alley, S., Kwong, J. C., Nasreen, S., Calzavara, A., Lu, D., Harris, T. M., Yu, K., & Wilson, S. E. (2022). Epidemiology of myocarditis and pericarditis following mrna vaccination by vaccine product, schedule, and interdose interval among adolescents and adults in ontario, canada. JAMA Network Open, 5(6), e2218505. https://doi.org/10.1001/jamanetworkopen.2022.18505
