From 1962 to 1987 most Japanese schoolchildren were vaccinated against influenza; at one point the vaccine was mandatory for a solid decade. The vaccination rate grew to around 85 percent, but the mandatory vaccination program was discontinued in 1994. Over the next several years, there was an increase in the number of deaths in the elderly during the flu seasons. In the U.S., where there had been no change in the vaccination policy, deaths of the elderly over the same flu seasons remained unchanged. Vaccinating one part of the population, in other words, benefits another.
