In the U.S.—

In Canada—

• Immunizing agent, active

Japanese encephalitis (in-cef-a-LY-tis) virus vaccine is an immunizing agent used to help prevent infection by the Japanese encephalitis virus. Japanese encephalitis is caused by the bite of a mosquito that lives in certain parts of Asia. The vaccine works by causing your body to produce its own protection (antibodies) against the virus.

This vaccine is available only from your doctor or other authorized health care professional, in the following dosage form:

Parenteral
• Injection (U.S. and Canada)

In deciding to use a medicine, the risks of receiving the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For Japanese encephalitis virus vaccine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to thimerosal, formaldehyde, gelatin, or rodent protein or brain products. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies on effects in pregnancy have not been done in either humans or animals.

Breast-feeding—It is not known whether this vaccine passes into breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are receiving this vaccine and who wish to breast-feed should discuss this with their doctor.

Children—Studies on this vaccine have been done only in adults and children 1 year of age and older. There is no specific information comparing use of this vaccine in infants under 1 year of age with use in other age groups.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of Japanese encephalitis virus vaccine in the elderly with use in other age groups, this vaccine is not expected to cause different side effects or problems in older people than it does in younger adults. In addition, immunization may be especially useful for the elderly, since older persons may have a higher risk of illness following infection with the Japanese encephalitis virus.

• Hives (history of)—May increase the chance of side effects of the vaccine

It is important that you receive 3 doses of the vaccine . If there is not enough time for you to get all 3 doses, you may get 2 doses of the vaccine. However, 2 doses of the vaccine will not protect you as well as 3 doses.

It is important that you receive all 3 doses of the vaccine at least 10 days before you plan on traveling out of the country. There is a chance of side effects that do not show up right away, and, if they do occur, they may need medical attention. In addition, the 10 days will give your body time to produce antibodies against the Japanese encephalitis virus.

Dosing—

The number of doses you receive and the time allowed between doses of Japanese encephalitis virus vaccine will be different for different patients.

• For help preventing Japanese encephalitis:
  • For injection dosage form:
    • Adults and children 1 year of age and older—One dose injected under the skin on days zero, seven, and thirty, for a total of three doses.
    • Children up to 1 year of age—Use and dose must be determined by your doctor.

Since the vaccine may not protect everyone completely, it is very important that you still use precautions to reduce your chance of mosquito bites. These include using insect repellents and mosquito netting, wearing protective clothing, and staying indoors during twilight and after dark.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. It is very important that you tell your doctor about any side effect that occurs after a dose of the vaccine, even if the side effect goes away without treatment. Some types of side effects may mean that you should not receive any more doses of the vaccine.

Get emergency help immediately if the following side effect occurs:

• Rare
  • Swelling of face, lips, eyelids, throat, tongue, hands, or feet  
  
  

Check with your doctor immediately if any of the following side effects occur:

• Rare
  • Hives;  tiredness or weakness (severe or unusual);  wheezing or troubled breathing 
  
  

Although the following side effects usually do not need medical attention and may go away on their own, their presence may also mean that more serious side effects are about to occur. Therefore, check with your doctor as soon as possible if any of the following side effects occur:

• More common
  • Tenderness, soreness, redness, or swelling at place of injection  
  
  

• Less common
  • Abdominal pain;  aches or pains in muscles ;  chills or fever;  dizziness ;  general feeling of discomfort or illness;  headache;  itching or skin rash;  nausea or vomiting 
  
  

• Rare
  • Joint swelling 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.