Efficacy and Safety of COVID-19 Vaccines in Adolescents: Systematic Review of Randomized Controlled Studies and Observational Studies

Abstract

The number of pediatric coronavirus disease 2019 (COVID-19) cases worldwide are increasing compared to the early phase of the pandemic, along with highly transmissible severe acute respiratory syndrome coronavirus variant and the increase in adult COVID-19 vaccination. We conducted a rapid systematic review and meta-analysis of published randomized clinical trials (RCTs) of the COVID-19 vaccines and the observational retrospective studies on adverse events after COVID-19 vaccination in adolescents. Seventeen studies were finally included in this systematic review. Meta-analysis showed that although vaccination in adolescents was significantly effective to prevent COVID-19 infection in retrospective studies (risk ratio [RR], 0.29; 95% confidence interval [CI], 0.22–0.37; I2=100%), however the effect of preventing COVID-19 infection was lower than in RCTs (RR, 0.05; 95% CI, 0.01–0.27). In five retrospective studies, the pooled estimated proportion of participants with myocarditis and/or pericarditis was 2.33 per 100,000 of the population (95% CI, 0.97–5.61 per 100,000). Sub-group analysis with sex and vaccine doses showed that male (5.35 per 100,000) and the second dose (9.71 per 100,000) had significantly higher incidence of myocarditis and/or pericarditis than female (1.09 per 100,000) and the first dose (1.61 per 100,000), respectively. Our study showed that mRNA COVID-19 vaccines in adolescent recipients were favorable and effective against COVID-19 in RCT as well as observational studies. The safety findings of BNT162b2 vaccine in adolescents were explored and we found the difference of safety according to sex and vaccine doses. The occurrence of adverse events after mRNA COVID-19 vaccination should be monitored.