Japanese Encephalitis (JE) Vaccine

What Is Japanese Encephalitis (JE)?

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.

What Is the Japanese Encephalitis (JE) Vaccine?

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.

Who Should Get Vaccinated and When?

The JE vaccine is advised for those traveling to Asia who are:

  • Planning to stay at least a month—in areas where there has been JE
  • Planning on staying less than a month—but will be in rural areas or outdoors a lot
  • Going to an area of JE outbreaks
  • Unsure where they will be staying

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.

What Are the Risks Associated With the Japanese Encephalitis (JE) Vaccine?

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:

  • Soreness, redness, or swelling near the injection site
  • Headache
  • Muscle pain

Who Should Not Get Vaccinated?

Talk to your doctor before getting the vaccine if you:

  • Have ever had a life-threatening reaction to this vaccine
  • Have severe allergic reactions
  • Are pregnant
  • Will be traveling to an urban area for less than 30 days

What Other Ways Can Japanese Encephalitis (JE) Be Prevented Besides Vaccination?

The vaccine is not 100% effective at preventing the disease. It is important to help prevent mosquito bites by:

  • Covering up the skin
  • Using bug sprays, netting, and screens
  • Staying inside between dusk and dark

What Happens in the Event of an Outbreak?

If there is a JE outbreak, those who can get the vaccine should get it.

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: . Accessed August 23, 2021.
Japanese encephalitis. Centers for Disease Control and Prevention website. Available at: Accessed August 23, 2021.
Japanese encephalitis VIS. Centers for Disease Control and Prevention website. Available at: Accessed August 23, 2021.
Mosquito avoidance. EBSCO DynaMed website. Available at: Accessed August 23, 2021.
Last reviewed July 2021 by EBSCO Medical Review Board David L. Horn, MD, FACP
Last Updated: 8/23/2021