Adverse reactions to the BNT162b2 and mRNA-1273 mRNA COVID-19 vaccines in Japan

Introduction: The BNT162b2 and mRNA-1273 COVID-19 vaccines are the main vaccines that have been used for mass vaccination in Japan. Information on adverse reactions to COVID-19 vaccines in the Japanese population is limited. Methods: We conducted an online survey on self-reported adverse reactions in individuals who had received two doses of the BNT162b2 or mRNA-1273 vaccine. The incidence of adverse events after each dose of vaccine was investigated. Propensity score matching was used to compare the incidence of adverse reactions after the second dose of the BNT162b2 and mRNA-1273 vaccines. Results: After the first and second doses of the BNT162b2 vaccine, and the first and second doses of the mRNA-1273 vaccine, 890, 853, 6401, and 3965 individuals, respectively, provided complete responses. Systemic reactions, including fever, fatigue, headache, muscle/joint pain, and nausea were significantly more common in females, individuals aged <50 years, and after the second dose. The incidence of injection site pain did not differ significantly according to the dose. The incidence of delayed injection site reactions after the first dose of mRNA1273 vaccine was 3.9% and 0.8% among females and males, respectively, and 10.6% among females aged 40-69 years. Local and systemic reactions after the second dose, including fever, fatigue, headache, muscle/joint pain, nausea, and skin rash were more common in individuals who had received the mRNA-1273 vaccine. Conclusions: Adverse reactions were more frequently reported in females, younger individuals, and after the mRNA-1273 vaccine.