Japanese encephalitis (JE) is an infection from a mosquito bite. Most have no symptoms. Some have mild symptoms such as a headache or fever. Rarely, it can affect the brain and nervous system. When this happens, it can be serious and even life-threatening.
The vaccine is made from an inactive form of the virus. It is called Ixiaro. It is for people ages 2 months of age and older. It is only available in the U.S.
IMOJEV is a vaccine made from live, weakened virus. It is not available in the United States.
The JE vaccine is advised for those traveling to Asia who are:
Lab workers who may be exposed to the JE virus should also get the vaccine.
The JE vaccine is given in a series of 2 shots within 28 days. The last dose needs to be given within 1 week of traveling to Asia.
A booster dose (third dose) is advised after a year or more. This is ONLY for those with an ongoing risk of exposure to the JE virus.
Like any vaccine, the JE vaccine can cause problems. Examples are severe allergic reactions. The risk of serious harm or death is very small.
Most reported problems from the JE vaccine are mild. They include:
Talk to your doctor before getting the vaccine if you:
The vaccine is not 100% effective at preventing the disease. It is important to help prevent mosquito bites by:
If there is a JE outbreak, those who can get the vaccine should get it.
WHERE CAN I GET MORE INFORMATION?
Centers for Disease Control and Prevention
Immunization Action Coalition
Hills SL, Walter EB, et al. Japanese encephalitis vaccine: recommendations of the advisory committee on immunization practices. MMWR Recomm Rep. 2019;68(2):1-33.
Immunization schedules. Centers for Disease Control and Prevention website. Available at:https://www.cdc.gov/vaccines/schedules/index.html . Accessed August 23, 2021.
Japanese encephalitis. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/japaneseencephalitis/. Accessed August 23, 2021.
Japanese encephalitis VIS. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/hcp/vis/vis-statements/je-ixiaro.pdf. Accessed August 23, 2021.
Mosquito avoidance. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/mosquito-avoidance. Accessed August 23, 2021.
Last reviewed July 2021 by
EBSCO Medical Review Board
David L. Horn, MD, FACP
Last Updated: 8/23/2021