Japan has a really old population which makes this a major concern for them (median age >50 a decade more than the US). It makes it also harder extrapolating th

Japan has a really old population which makes this a major concern for them (median age >50 a decade more than the US). It makes it also harder extrapolating this to other countries. Density of susceptible persons makes a difference when it vomes to spreading (herd immunity, hospital transmissions).