Intramuscular vs. Subcutaneous: Rethinking Influenza Vaccination Strategy in Japan.

In Japan, inactivated vaccines, including the influenza vaccine, are administered subcutaneously, which is contrary to global recommendations for intramuscular injections. This practice is attributed to historical medical incidents and unchallenged conventions. However, this outdated method, which differs from that of international standards and is linked with less immunogenicity and more adverse reactions, may contribute to vaccination hesitancy. Therefore, with the adoption of intramuscular vaccination administration, which was widely adopted in the coronavirus disease 2019 vaccination, a shift in the Japanese health policy to conform to international standards potentially improves vaccine acceptance and effectiveness.