Japan’s Measles Infection Rate Increasing Due to International Travelers, Drop in Vaccination Rate

By Naoko Kagemoto and Makoto Akino / Yomiuri Shimbun Staff Writers

15:57 JST, April 23, 2026

Although measles has been declared “eliminated” in Japan, cases are rising sharply this year.

In recent years, people infected overseas have brought the measles virus into the country, and group infections have occurred in some areas. Measles is highly contagious and in rare cases can cause serious complications such as inflammation of the brain. The only effective way to combat the spread of infections is vaccination and the Health, Labor and Welfare Ministry is calling for children to be vaccinated.

Measles is spread through airborne transmission — the virus can be breathed in while it floats in the air — among other ways. It is believed that one measles patient can, on average, pass on the virus to 12 to 18 non-immune individuals and the virus is about 10 times more contagious than influenza.

Although 744 measles cases were reported across the nation in 2019, there were 10 or fewer recorded in each of the three following years. However, cases began increasing in 2023 and climbed to 265 in 2025. This year, the number of cases has already reached 299 as of April 12. A cluster of infections was detected at an elementary school in the Tokyo metropolitan area this month.

In 2015, the World Health Organization declared that Japan had “eliminated” measles, which is defined as the absence of the continuous transmission of the disease within a defined geographical region. This status will be withdrawn if sustained transmission of measles occurs for at least 12 months. An expert panel at the health ministry has expressed concern that Japan could lose its elimination status if infections continue to increase.

The number of measles cases is on the uptick around the world. Many developing nations have low vaccination rates, and India and Indonesia have reported significant outbreaks. Measles cases have also been increasing even in advanced nations in recent years. Britain and Canada have both lost their measles-free status.

The surge in international travel in the past few years has resulted in people bringing the virus into Japan.

91% vaccinated

The decline in vaccination rates is also contributing to the rise in measles cases. Receiving two doses of the measles vaccine is believed to lower the risk of developing symptoms or serious complications. In Japan, people can receive two doses as part of the publicly funded routine vaccination program: one at age 1, and another before starting elementary school. Although the health ministry has set a goal of having at least 95% of eligible people receive both doses, the actual figure stood at 91% in fiscal 2024.

The Japan Institute for Health Security surveyed local governments in areas where the vaccination rate was below 90%. The main reasons people in these areas cited for not getting vaccinated included, “There haven’t been any outbreaks recently, so people weren’t so worried about it” and “Information critical of vaccines has been going around.”

Norio Ohmagari, head of the institute’s department of infectious disease clinical policy, said, “If many people travel abroad during the upcoming long holiday period, it’s possible that cases in Japan will surge further.”

Vaccination rates vary

The health ministry has been urging parents and other parties to ensure that children receive routine vaccinations to help prevent the spread of measles. The ministry recommends that children are vaccinated during the health checkup conducted before they begin elementary school. The ministry has also prepared posters written in multiple languages to inform non-Japanese residents.

People not covered by the routine vaccination program can receive the vaccine at their own expense.

“There are disparities in vaccination rates among prefectures,” said International University of Health and Welfare Prof. Tetsuya Matsumoto, an expert on infectious diseases. “It’s vital that the central and local governments work together, carefully analyze the causes of low vaccination rates and then implement measures to address this problem. They also need to use social media and other channels to provide reliable information.”