Since December 2019, COVID-19, caused by SARS-CoV-2 infection, has been a major health threat worldwide (Hayakawa et al., 2020). The mRNA-based BNT162b2 mRNA COVID-19 vaccine has demonstrated a high efficacy rate with an acceptable safety profile (Polack et al., 2020). In Japan, a nationwide mass BNT162b2 mRNA vaccination campaign was launched and rolled out at an exceptionally rapid pace with high vaccine acceptance. As of June 13, 2021, 14.0% (n=17 580 587) and 4.9% (n=6 104 732) of the population had received their first and second vaccine dose, respectively (Ministry of Health, Labour and Welfare, Japan, 2021).
