Measurement of multiple SARS-CoV-2 antibody titer after vaccination represents individual vaccine response and contributes to individually appropriate vaccination schedules

The SARS-CoV-2 mRNA vaccine BNT162b2 (Pfizer-BioNTech) has become a game-changer in the COVID-19 crisis. Faster and wider coverage of vaccine supply is urgently needed, although vaccine supply is far from abundant in many countries and regions. There is no denying that Japan is vaccinating at a slower pace than in many other countries. At the end of April 2021, it had administered less than 2% of the population, according to the statistics website Our World in Data.1 Single-dose vaccination may be considered to induce an adequate antibody response in individuals with prior infection,2-5 which can lead to more effective vaccine distribution to people in serious need. However, multiple antibody responses in populations with various backgrounds, including prior COVID-19 infection, underlying diseases, and age, have not been investigated sufficiently. Due to the lack of antibody measurement data, antibody follow-up measurement recommendations have yet to be suggested. Accumulation of available data regarding quantitative antibody titer will lead to the establishment of personally customized schedules, including antibody follow-up, and will balance both faster delivery of vaccines and confirmation of effective vaccination.