Drug information of Japanese Encephalitis Virus Vaccine

Japanese Encephalitis Virus Vaccine

Drug group: Vaccines

Japanese encephalitis is a serious disease caused by a virus. It is the leading cause of viral encephalitis (inflammation of the brain) in Asia. Encephalitis is an infection of the membrane around the brain and spinal cord. This infection often causes only mild symptoms, but prolonged swelling of the brain can cause permanent brain damage or death.

Japanese encephalitis virus is carried and spread by mosquitoes.

The Japanese encephalitis SA14-14-2 vaccine is used to help prevent this disease in adults and adolescents who are at least 17 years old.

This vaccine works by exposing you to a small dose of the virus, which causes the body to develop immunity to the disease. This vaccine will not treat an active infection that has already developed in the body.

This vaccine is recommended for people who live in or travel to areas where Japanese encephalitis is known to exist, or where an epidemic has recently occurred.

You should receive the vaccine and booster dose at least 1 week prior to your arrival in an area where you may be exposed to the virus.

Not everyone who travels to Asia needs to receive a Japanese encephalitis vaccine. Follow your doctor instructions or the recommendations of the Centers for Disease Control and Prevention (CDC).

This vaccine is also recommended for people who work in a research laboratory and may be exposed to Japanese encephalitis virus through needle-stick accidents or inhalation of viral droplets in the air.

Like any vaccine, the Japanese encephalitis SA14-14-2 vaccine may not provide protection from disease in every person.

Mechanism of effect

This vaccine induces antibodies to neutralize the Japanese encephalitis virus. Antibody response is measured using a 50% plaque-reduction neutralization antibody test (PRNT50); a threshold of ≥1:10 is considered protective immunity.


Onset of Action

Protective immunity was observed in ≥95% of children and adults (<65 years of age) 28 days after the second vaccine dose.

Duration of Action

Protective immunity was observed in ~80% to 85% of adults 12 to 36 months after the initiation of the two-dose series. In 96% of adults, seroprotection was shown to last ≥6 years after a booster dose administered 15 months after the first dose of a two-dose primary series. In children, 100% were reported to be seroprotective up to 24 months after the booster dose; pharmacodynamic modeling suggest median duration of seroprotection of 9 years in children .

Drug indications

Labeled Indications

Japanese encephalitis prevention: Active immunization against Japanese encephalitis (JE) for persons ≥2 months of age.

The Advisory Committee on Immunization Practices (ACIP) recommends vaccination for (CDC/ACIP [Hills 2019]):

- Persons moving to or frequently traveling to JE-endemic areas

- Persons spending ≥1 month in endemic areas

- Laboratory workers who may be exposed to the JE virus other than SA14-14-2 JE vaccine virus. For those working with SA14-14-2 JE virus, vaccination should be considered for those working with high concentrations or volumes or passaging virus. Note: Vaccination not required for workers handling routine clinical samples.

- Persons traveling for shorter periods of time (eg, <1 month) who are at increased risk for JE based on travel duration, season, location, activities, accommodations or those with uncertain travel itineraries should consider vaccination. Note: Not recommended for very low-risk travelers (eg, those traveling for shorter terms and only to urban areas or periods outside of the well-defined JE virus transmission season).


Usual Adult Dose for Japanese Encephalitis Virus Prophylaxis

Primary Series: Two 0.5 mL doses intramuscularly 28 days apart

Booster Dose: May give a booster dose if the primary 2 dose series was completed more than 1 year previously and ongoing exposure to Japanese encephalitis virus (JEV) is expected.

Comments: The primary immunization series should be completed at least 1 week prior to potential exposure.

Usual Pediatric Dose for Japanese Encephalitis Virus Prophylaxis

Primary Series:
3 years of age and older: Two 0.5 mL doses intramuscularly 28 days apart
2 months to less than 3 years of age: Two 0.25 mL doses intramuscularly 28 days apart

Booster Dose:
17 years of age and older: May give a booster dose if the primary 2 dose series was completed more than 1 year previously and ongoing exposure to Japanese encephalitis virus (JEV) is expected.
2 months to under 17 years: The safety and immunogenicity of a booster dose has not been evaluated.

Comments: The primary immunization series should be completed at least 1 week prior to potential exposure.

Drug contraindications

Severe allergic reaction to a previous dose of the vaccine, any other Japanese encephalitis virus vaccine, or any component of the vaccine, including protamine sulfate.

Canadian labeling: Additional contraindications (not in US labeling): Hypersensitivity to a previous dose of the vaccine or to any component of the formulation; acute severe febrile conditions

Side effects

You should not receive a booster vaccine if you had a life-threatening allergic reaction after the first shot.

Keep track of any and all side effects you have after receiving this vaccine. When you receive a booster dose, you will need to tell the doctor if the previous shot caused any side effects.

Becoming infected with Japanese encephalitis is much more dangerous to your health than receiving this vaccine. However, like any medicine, this vaccine can cause side effects but the risk of serious side effects is extremely low.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; dizziness, weakness, fast heart rate; swelling of your face, lips, tongue, or throat.

Common side effects may include:

  • headache, tired feeling;
  • muscle pain, backpain;
  • low fever, chills, flu symptoms;
  • cold symptomssuch as stuffy nose, sneezing, sore throat, cough;
  • mild itching or skin rash;
  • nauseadiarrhea; or
  • pain, redness, tenderness, or a hard lump where the shot was given.



You should not receive this vaccine if you have ever had a life-threatening allergic reaction to any vaccine containing Japanese encephalitis virus.

If you have any of these other conditions, your vaccine may need to be postponed or not given at all:

  • a bleeding or blood clotting disorder; or
  • a weak immune system caused by disease or by taking certain medicines or receiving cancer treatments.

Points of recommendation

IM: For IM injection. Do not inject IV, SubQ, or intradermally. Shake well prior to use to form a homogeneous suspension. Do not use if discolored or if particulate matter remains. Do not mix with other vaccines or injections; separate needles and syringes should be used for each injection .

The preferred site for administration is the deltoid muscle. To prevent syncope related injuries, patients should be vaccinated while seated or lying down .

You can still receive a vaccine if you have a minor cold. In the case of a more severe illness with a fever or any type of infection, wait until you get better before receiving this vaccine.

Vaccines may be harmful to an unborn baby and generally should not be given to a pregnant woman. However, not vaccinating the mother could be more harmful to the baby if the mother becomes infected with a disease that this vaccine could prevent. Your doctor will decide whether you should receive this vaccine, especially if you have a high risk of infection with Japanese encephalitis virus.

Do not receive this vaccine without telling your doctor if you are breast-feeding a baby.

This vaccine is injected into a muscle. You will receive this injection in a doctor's office or clinic setting.

The Japanese encephalitis SA14-14-2 vaccine is given in a series of 2 shots. The shots are usually 28 days apart. Your individual booster schedule may be different from these guidelines. Follow your doctor's instructions or the schedule recommended by the health department of the state you live in.

In addition to receiving the Japanese encephalitis vaccine, use protective clothing, insect repellents, and mosquito netting around your bed to further prevent mosquito bites that could infect you with the Japanese encephalitis virus.

Contact your doctor if you miss a booster dose or if you get behind schedule. The next dose should be given as soon as possible. There is no need to start over.

Be sure to receive all recommended doses of this vaccine. You may not be fully protected if you do not receive the full series.



Store in original packaging under refrigeration at 2°C to 8°C (35°F to 46°F); do not freeze. Protect from light. A clear liquid with a white precipitate can be observed during storage.

Pregnancy level


This drug should be used during pregnancy only if clearly needed.

AU TGA pregnancy category: B1
US FDA pregnancy category: B

Breast feeding warning

Caution is recommended

Excreted into human milk: Unknown
Excreted into animal milk: Data not available

Drug forms

• Ixiaro

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