Fig. 1

Epidemic curve of hepatitis A in Japan in 2018 by week, age, and sex distribution. A Temporal distribution of the incidence (serologically diagnosed cases) from 2017 to 2018. B Age distribution of serologically diagnosed cases. The data from 2017 are based on whole-year notifications, but the 2018 data were gathered only up to July 26th. In 2017, the age distribution was fairly flat for women and peaked at 35–39 years for men, and the male-to-female ratio was not particularly high. In contrast, most cases in 2018 occurred in young men aged 20–55 years. C Spatial distribution of serologically diagnosed cases from 2017 to 2018. Many cases were diagnosed in the Kanto region, which includes the Tokyo metropolitan area, followed by Osaka Prefecture, the third largest prefecture in western Japan. D Sex distribution of confirmed cases from 2006-19. Proportion male is measured on right vertical axis