The increase in the number of rubella patients continues unabated since it spiked in late July mainly in the Tokyo metropolitan area. According to the National Institute of Infectious Diseases, the cumulative number of patients this year reached 1,692 at the end of last month — 18 times more than the figure of the whole year of 2017 and the largest since the last major outbreak in the 2012-13 period, when the nation had roughly 16,700 patients in two years. Rubella cases have been reported throughout the country.

The latest outbreak of rubella, if protracted, could threaten the government's target of eliminating the disease in Japan by fiscal 2020, and also raise concern about the possibility of an outbreak occurring just as the nation hosts the 2020 Tokyo Olympic and Paralympic Games. Concerned parties need to take prompt action to contain the infection, in particular by ensuring that men in their 30s to 50s who, compared with other generations, are believed not to have been sufficiently vaccinated against the highly contagious disease, take the necessary measures to avoid infection. If carriers of the virus pass it on to pregnant women, there is a high risk that it could cause a range of serious fetal defects, including heart disorders, hearing impairment, eye problems, brain damage and even death.

The rubella virus is often transmitted through coughing and sneezing, and is more contagious than influenza. Although symptoms in children who contracted the disease tend to be minor such as rash and fever, the risk of causing congenital rubella syndrome (CRS) in the developing fetus is high if women who don't have sufficient immunity against the virus get infected by around the 20th week of their pregnancy. Although no cases of CRS have so far been reported in the latest outbreak, at least 45 babies were born with the syndrome during the 2012-13 outbreak, of whom 11 died.