[Epidemiology of measles in Japan].

As of May 2025, measles outbreaks have been occurring worldwide. Japan has reported the highest number of cases since the beginning of the COVID-19. Unvaccinated measles cases are highly contagious and at high risk for serious illness, so it is important to ensure that children receive the live attenuated measles-rubella (MR) vaccine as soon as they become one year old. Additionally, the second routine immunization coverage rate must be raised to 95% or higher among five-to six- year-old children (one year before entering elementary school). For elementary school students and older individuals, it is important to check the vaccine records showing two doses of a measles-containing vaccine administered at or after one year of age. Those born on or after April 2, 1990, had the opportunity to receive two routine vaccinations; however, their records must be checked to confirm receipt. We also recommend checking vaccination records before traveling abroad. Additionally, rapid active epidemiological surveillance should be conducted in the event of a single measles case. Emergency vaccination within 72 hours of exposure for susceptible individuals may prevent the disease. For individuals ineligible for vaccination, health insurance covers the prevention of severe disease through an intramuscular injection of human immunoglobulin within six days of exposure. The most important measure is prophylaxis prior to exposure to the measles virus.