Age specificity of cases and attack rate of novel coronavirus disease (COVID-19)

Age distribution of the cases with novel coronavirus disease (COVID-19) is rather different from that of influenza. In China, there were few reported cases among children [1] and serious or fatal child cases were also very infrequent. The age specificity is particularly important in designing details of social distancing, including school closure, as interventions, which is now recognized as the mainstream of interventions against COVID-19. Investigating the details of contacts, substantial susceptibility among children was demonstrated [2], but further insights into underlying mechanisms should be explored. Here we examined the age distribution of COVID-19 cases in Japan from January to March, 2020.