Japanese Encephalitis Vaccine

Japanese encephalitis vaccine is a vaccine that protects against Japanese encephalitis, and the available vaccines are more than 90 percent effective, although the duration of protection is unclear and effectiveness appears to decrease over time. Doses are given either by injection into a muscle or just under the skin, and the vaccine is recommended as part of routine immunization in countries where the disease is a problem, with one or two doses given depending on the version used. People with HIV/AIDS or who are pregnant should receive an inactivated version, and immunization is also recommended for travelers who plan to spend time outdoors in areas where the disease is common. As of 2015, fifteen different vaccines were available, based variously on recombinant DNA techniques, weakened virus or inactivated virus. Japanese encephalitis vaccines first became available in the 1930s, and the vaccine is on the World Health Organization's List of Essential Medicines.