Adverse events post-BNT162b2 vaccination in Japanese children

BNT162b2 vaccination rates are low in Japanese children owing to concerns regarding adverse events (AEs). There are few reports indicating AE incidence post-vaccination in Japanese children, and the risk factors for AEs remain unclear. We aimed to elucidate AE incidence and risk factors post-BNT162b2 vaccination in Japanese children.

Children aged 6 months-11 years who received the BNT162b2 vaccine at 12 collaborating institutions were targeted. An AE was defined as any untoward medical occurrence post-vaccination, not necessarily caused by the vaccination. AEs at 7 days post-BNT162b2 vaccination were recorded and reported via an online form.

Data of 1016 Japanese children were analyzed (465, 318, and 233 children had vaccination for dose 1, 2, and 3, respectively). The incidence of fever (≥37.5 °C) post doses 1, 2, and 3 was 6.2 %, 14.1 %, and 18.0 %, respectively. No severe AEs, such as myocarditis, anaphylaxis, or seizures were observed. Older age, female sex, higher BNT162b2 dose, previous vaccination, medical history (anaphylaxis, immune thrombocytopenia, allergic diseases, and epilepsy), and AEs in parents were associated with an increased risk of AEs.

BNT162b2 vaccination in Japanese children was safe. The overall low AE rates and increased knowledge of the patterns and factors associated with AEs may enhance public confidence in vaccination and promote greater uptake of coronavirus disease (COVID-19) vaccination in Japanese children, thus enhancing COVID-19 control.