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Rubella incidence in Japan on the rise
As of 2013, two WHO regions have established goals to eliminate rubella, the region of the Americas by 2010 and the European region by 2015. Targets also have been established by the Western Pacific region for accelerated rubella control and congenital rubella syndrome prevention, according to a recent Morbidity and Mortality Weekly Report.
A measles-mumps-rubella vaccine was introduced in 1989 targeting children aged 12 to 72 months, but adult males remain susceptible. Japan introduced a single-antigen rubella vaccine into its national immunization program targeting girls in junior high school in 1976.
From Jan. 1 to May 1, 2013, 5,442 rubella cases were reported through the surveillance system in Japan, 77.4% of which occurred in males and 72.3% were laboratory confirmed.
“In the current outbreak, males aged 20 to 39 years, who were not included in the initial rubella vaccination program, accounted for 68% of the reported cases,” researchers wrote. “However, with the introduction of two doses of [measles-rubella] vaccine into the national vaccination schedule in 2006 for both boys and girls and the successful catch-up vaccination program, children who currently are aged <15 years account for only 5.6% of the cases.”
From October 2012 to May 1, 2013, 10 infants were reported with congenital rubella syndrome. Six of the infants’ mothers had not been vaccinated.
Researchers said, until the early 2000s, rubella was mostly endemic in Japan with periodic epidemics occurring almost every 5 years with seasonal increases in the spring and summer. The number of rubella cases increased to 2,392 in 2012, and the rise continued into 2013.
The measles-rubella vaccine coverage in 2011 was 95.3% for children aged 1 year, 92.8% for those aged 5 to 6 years, 88.1% for those aged 12 to 13 years and 81.4% for those aged 17 to 18 years.
“The international spread of rubella virus from Japan provides a reminder that countries in regions that have eliminated rubella need to maintain high levels of vaccination coverage and high-quality surveillance to limit the spread and detect important rubella virus,” researchers wrote.
Disclosure: The researchers report no relevant financial disclosures.
