Japanese Encephalitis Vaccine

Japanese Encephalitis Information

Japanese encephalitis is a serious infection caused by a virus that is present in many parts of Asia. The Japanese encephalitis virus (JEV) is spread between mosquitoes and animals such as pigs and wading birds. Although the mosquitoes prefer to feed on large domestic animals, if an infected mosquito bites a human, it can lead to infection and illness. The infection cannot be spread from person to person.

Most people who become infected do not have any symptoms, but a small number do experience some symptoms, such as fever and headache. The most common complication of JEV infection is encephalitis, or swelling of the brain. About 25 percent of cases with severe infections of encephalitis can result in death.

Japanese Encephalitis Vaccine Information

Japanese encephalitis vaccine is an inactivated vaccine. Although it can prevent JEV infection, it is not 100 percent effective and is not a substitute for taking proper precautions against mosquitoes.

The vaccine is given as an injection into the deltoid muscle which is known as an intramuscular injection. The two-dose vaccination must be completed at least one week before travel.

Who Should Receive the Japanese Encephalitis Vaccine?

  • Anyone age 17 and older who plans to live or travel in rural areas of Asia where JEV is prevalent
  • Laboratory workers who work with JEV

Japanese Encephalitis Vaccination Schedule

  • Two doses: First dose, followed by a second dose 28 days after the first dose, with the last dose given at least 1 week before travel
  • A booster dose may be given to anyone who was vaccinated more than one year ago and is still at risk of exposure, or might be re-exposed.

Japanese encephalitis vaccine may be given at the same time as other vaccines.

Side Effects

Mild-to-Moderate Problems

  • Soreness, redness, or swelling where the shot was given
  • Headache and muscle aches

Severe Problems (Rare)

  • High fever or behavior changes.
  • Difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat or dizziness.

Over-the-counter pain relievers such as acetaminophen or ibuprofen can help ease pain and reduce fever.

It is extremely rare for this vaccine to cause serious harm or death. If the person getting the vaccine has a serious reaction, call the doctor or seek immediate medical attention.

Who Should Not Receive the Japanese Encephalitis Vaccination

  • Those with moderate or severe illness (for example, a severe cold, flu or infection of the sinuses or lungs) should not receive the vaccine until symptoms of the illness improve.
  • Women who are pregnant or plan to become pregnant should ask their doctor if they should receive the vaccine.
  • Those with a history of developing a rash or wheezing after being stung by a wasp or after taking certain medications
  • Those who previously had a severe, life-threatening allergic reaction to the vaccine or any ingredient in the vaccine should not be vaccinated.

Additional Information

Tell your doctor or a healthcare provider if the person getting the vaccine has any severe allergies.

Call the Centers for Disease Control and Prevention (CDC) at 800-232-4636 or visit the CDC website, at  cdc.gov/vaccines, for more vaccine information.

This publication should be used for general educational purposes only and is not intended to be a substitute for professional medical advice. Be sure to contact your doctor, pharmacist, or other healthcare provider for more information about human papillomavirus. Although it is intended to be accurate, neither Walgreen Co., its subsidiaries or affiliates, nor any other party assumes liability for loss or damage due to reliance on this publication.


Centers for Disease Control and Prevention (CDC). Health Information for International Travel 2008. Atlanta: US Department of Health and Human Services. Public Health Services, 2007.

Vaccine Information Statement: Japanese encephalitis vaccine. Centers for Disease Control and Prevention (CDC). May 11, 2005. cdc.gov/vaccines/pubs/vis/default.htm. Accessed April 2008.

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