Figure 1.

Vaccinated populations, daily new cases in Japan, and schedules of vaccination and blood sampling in the study participants. “▲” indicates participants who had SARS-CoV-2 infection confirmed by PCR after vaccination. The triangle also indicates the timing of the diagnosis. * The number in the parentheses includes 11 participants with a history of positive PCR results and 2 with positive anti-N antibody results without PCR positive results. ** The number in the parentheses includes 7 participants with a history of positive PCR results, 1 with a history of positive anti-N antibody results without PCR positive results, and 5 newly infected and confirmed by PCR after the first testing. (https://news.yahoo.co.jp/pages/article/20200207, accessed on 6 January 2022; https://www.worldometers.info/coronavirus/country/japan/, accessed on 6 January 2022).