Japanese encephalitis vaccine
Japanese encephalitis is a serious infection caused by a virus present in many parts of Asia. The virus is spread between
mosquitoes and animals, such as pigs and wading birds. If an infected mosquito bites a human, it can lead to infection
and illness, but the infection cannot be spread from person to person.
Most people who become infected have no symptoms, although some may experience fever and headache. The most
common complication is swelling of the brain. About 25 percent of cases with severe encephalitis infections can result
in death.
The Japanese encephalitis vaccine is an inactivated vaccine that is very effective at preventing infection. It’s a 2-dose vaccine administered 28 days apart. The second dose must be completed at least 1 week before travel. The vaccine is CDC-approved for people ages 2+ months.
• Travelers ages 2+ months who plan to live or travel to rural areas of Asia where the virus is prevalent
• People who remain at risk of exposure 1 year after their initial 2 doses
• Laboratory workers who may have been exposed to the virus
• Anyone with moderate or severe illness should wait until they recover to be vaccinated
• Anyone with a life-threatening allergy to any vaccine component, such as protamine sulfate, or any ingredient in the vaccine
Mild-to-moderate side effects:
• Soreness, redness or swelling at the injection site
• Headache, muscle aches or fever
Severe side effects, although rare, may include serious allergic reactions. Symptoms include:
• High fever or behavior changes
• Difficulty breathing, hoarseness or wheezing
• Hives
• Paleness
• Wheezing
• Fast heartbeat
• Dizziness
Over-the-counter pain relievers such as paracetamol or ibuprofen can help ease pain and reduce fever. Contact your doctor or pharmacist if you have any unexpected or worsening reactions after receiving a vaccine.