Myocarditis and pericarditis in adolescents after first and second doses of mRNA COVID-19 vaccines

AIMS: While some concerns about vaccination-related pericarditis and/or myocarditis have been raised, no published data are available on pericarditis and/or myocarditis with mRNA COVID-19 vaccines in the age group of adolescents, particularly 12-15 years. The objective of this study was to determine whether the risk of reporting pericarditis and/or myocarditis with mRNA COVID-19 vaccines varied according to dose of vaccination, age, sex, and type of pericarditis and/or myocarditis in adolescents between 12 and 17 years. METHODS AND RESULTS: We performed an observational study reviewing all reports of adolescents vaccinated with mRNA COVID-19 vaccines and recorded in VigiBase®, the World Health Organization global database of individual case safety reports. We included all reports registered between 1 January 2021 and 14 September 2021. Reporting odds ratios (RORs) with their 95% confidence interval (CI) were calculated to estimate the risk of reporting pericarditis and/or myocarditis. Among 4942 reports with mRNA COVID-19 vaccines in adolescents, we identified 242 pericarditis and/or myocarditis. Compared with the first dose of mRNA COVID-19 vaccines, the second dose was associated with an increased risk of reporting pericarditis and/or myocarditis (ROR 4.95; 95% CI 3.14, 7.89). The risk of reporting pericarditis and/or myocarditis was 10 times higher in boys than in girls and no difference between the two types of vaccines could be demonstrated. CONCLUSION: This investigation including only adolescent data suggests for the first time that the second dose of mRNA COVID-19 vaccines increases the risk of reporting myocarditis/pericarditis compared with the first dose particularly in boys without significant difference between tozinameran and elasomeran.