Adverse reactions to coronavirus disease 2019 vaccines in children and adolescents

The incidence of coronavirus diseases 2019 (COVID-19), including severe cases, has been increasing in both children and adolescents with the spread of the delta variant. COVID-19 vaccines have been identified to be effective in the prevention of COVID-19 transmission in children and adolescents and keeping schools open. However, adverse reactions associated with COVID-19 vaccination in children and adolescents contribute to parents' hesitation to proceed with vaccination, especially due to serious, albeit rare, reactions. The results from COVID-19 vaccine clinical trials on the safety and efficacy of COVID-19 vaccines in children and adolescents are promising in terms of their effects on COVID-19 infection prevention. In the present study, we summarize the adverse reactions of COVID-19 vaccines in children and adolescents, based on the clinical trials, mainly including Pfizer-BioNTech and Moderna COVID-19 vaccines. In the Pfizer-BioNTech COVID-19 clinical trials, the most common local adverse reaction was pain at the injection site in 74.1%-86%, depending on age, and the most common systemic adverse reaction was fatigue, followed by headache, myalgia, diarrhea, and fever with differences in the distribution according to age. There was no severe adverse reaction related to any COVID-19 vaccine in children and adolescents during the study period. In the mass vaccination program of COVID-19 in children and adolescent, myocarditis has rarely been diagnosed after COVID-19 vaccination, which most commonly occurred in boys after the second dose. Currently, Pfizer-BioNTech COVID-19 vaccines can be safely recommended in children and adolescents for the prevention of COVID-19 infection and the reduction in COVID-19 severity.