Time course of adverse reactions after BNT162b2 vaccination in healthy and allergic disease individuals aged 5–11 years: an observational and historical cohort study

Abstract

Purpose We aimed to assess whether BNT162b2 vaccination in children meets high safety standards by surveying adverse reactions in healthy and allergic disease individuals aged 5–11 years in Japan throughout seven days following their first and second BNT162b2 vaccination. Methods This was an observational and historical cohort study. The eligibility criteria of study participants included those aged 5–11 years, who received two doses of BNT162b2, with consent by the children and their guardians. We collected data on sex, age, height, weight, blood type, history of BCG vaccination, allergic disease, medication, history of COVID-19 infection and adverse reactions seven days following the first and second BNT162b2 vaccination using a questionnaire. We used previous reports to compare our result with individuals aged 12–15years. Results A total of 421 participants were eligible for this study. Among the 216 patients with allergic disease, 48 (22.2%) had experienced worsening of their chronic diseases, and the frequency of fatigue and dizziness after the second dose was higher than that of healthy individuals. The experience of systemic adverse reactions was associated with asthma. The frequency of headache, diarrhea, fatigue, muscle/joint pain, and fever after the second BNT162b2 vaccination was lower in the individuals aged 5–11 years than in those aged 12–15 years. Fever was the only systemic adverse reaction that lasted longer than five days (1.0% of participants). Conclusions Individuals with allergic diseases, who are potentially susceptible to COVID-19, may experience worsening of their chronic diseases and more frequent adverse reactions after BNT162b2 vaccination than healthy individuals. To ensure that children with allergic diseases receive the vaccine safely, further information needs to be collected.