Fig. 3

Case fatality risk and predicted number of deaths in Tokyo and Osaka, 2020–2022. A–C Show the case fatality risk (CFR) in Tokyo among the 60s, 70s, and 80 years and older age groups, respectively. D–F Indicate the CFR in Osaka among the 60s, 70s, and 80 years and older age groups, respectively. The dots show the observed number of daily deaths; the thin black curve indicates the expected number of deaths from our model. The light-grey shaded area represents the 95% confidence interval (CI) of daily deaths as computed by the parametric bootstrap method. The continuous step function shows the estimated CFR along with its 95% CI indicated as broken lines. If any dominant variant of concern was responsible, the horizontal arrow indicates the corresponding period. The CFR of the fourth wave (caused by the Alpha variant) yielded a higher CFR in Osaka than during the fifth wave. After the fifth wave (Delta variant), a substantial proportion of the population was protected