The Japanese Encephalitis Vaccine

Written by Amy Boulanger | Published on January 12, 2015
Medically Reviewed by George Krucik, MD, MBA on January 12, 2015

Japanese Encephalitis Vaccination

Japanese encephalitis (JE) is a virus transmitted through the bite of infected mosquitoes. It’s most commonly found in rice fields and other rural areas of Asia.

JE is closely related to the St. Louis and West Nile viruses. All three viruses cause acute inflammation of the brain and spinal column. Symptoms begin with fever and headache. However, they can turn into:

  • high fever
  • disorientation
  • tremors
  • stiff neck
  • convulsions
  • paralysis

According to the Centers for Disease Control and Prevention (CDC), a quarter of people who develop JE will die. Half will develop permanent brain damage.

Currently vaccination is only widely available for adults in the United States. The vaccine approved for children is no longer manufactured. If a child needs a vaccine, the options include:

  • off-label use of the adult vaccine
  • enrollment in a clinical trial
  • going to a travelers’ health clinic in Asia

Who Needs Vaccination?

Not everyone who travels to Asia needs to be vaccinated for JE. Vaccination is recommended only for those who are:

  • going to spend at least one month in an area where JE occurs
  • planning to visit any rural areas or engage in outdoor activities
  • visiting an area with a current JE outbreak
  • uncertain of their travel plans

The vaccine is given in two doses. The doses should be given at least 28 days apart. The second dose should be received at least one week before potential JE exposure. This means you need the first vaccine dose at least 35 days before the start of travel.

Who Should Not Be Vaccinated?

Certain people should not get the JE vaccination. This includes people who:

  • have had a serious reaction to a previous dose of the JE vaccine
  • are allergic to any vaccine components
  • are pregnant, except in certain circumstances

Talk to your doctor if you are planning only a short stay in Asia. If you are primarily visiting urban areas, you may not need the vaccine.

Potential Side Effects

Severe reactions to this vaccine are rare. However, many people have mild side effects including:

  • pain at the injection site
  • redness or swelling at the injection site
  • headaches
  • muscle aches
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