Encephalitis Vaccine is indicated for active immunisation against Japanese encephalitis in adults, adolescents, children and infants aged 2 months and older. Encephalitis Vaccine should be considered for use in individuals at risk of exposure through travel or in the course of their occupation.

The mechanism of action of Japanese encephalitis (JE) vaccines is not well understood. Studies in animals have shown that the vaccine triggers the immune system to produce antibodies against Japanese encephalitis virus that are most often protective. Challenge studies were performed in mice that were treated with human Encephalitis Vaccine antisera. These studies showed that almost all mice that had a Plaque Reduction Neutralization Test titre of at least 1:10 were protected from a lethal Japanese encephalitis virus challenge.

Adults (18 to ≤ 65 years of age): The primary vaccination series consists of two separate doses of 0.5 ml each, according to the following conventional schedule:

• First dose: Day 0.
• Second dose: 28 days after first dose.

Rapid schedule: Persons aged 18 to ≤65 years can be vaccinated in a rapid schedule as follows:

• First dose: Day 0.
• Second dose: 7 days after first dose.

With both schedules, primary immunisation should be completed at least one week prior to potential exposure to Japanese encephalitis virus (JEV). It is recommended that vaccinees who received the first dose of Encephalitis Vaccine complete the primary 2-dose vaccination course with Encephalitis Vaccine. If the primary immunization of two injections is not completed, full protection against the disease might not be achieved. There is data that a second injection given up to 11 months after the first dose results in high seroconversion rates.

Booster dose: A booster dose (third dose) should be given within the second year (i.e. 12-24 months) after primary immunization, prior to potential re-exposure to JEV. Persons at continuous risk for acquiring Japanese encephalitis (laboratory personnel or persons residing in endemic areas) should receive a booster dose at month 12 after primary immunization. Long-term seroprotection data following a first booster dose administered 12-24 months after primary immunization suggest that a second booster should be given 10 years after the first booster dose, prior to potential exposure to JEV.

Elderly (>65 years of age): The primary vaccination series consists of two separate doses of 0.5 ml each, according to the following conventional schedule:

• First dose: Day 0.
• Second dose: 28 days after first dose.

Pediatric Population:
Children and adolescents from 3 years to <18 years of age: The primary vaccination series consists of two separate doses of 0.5 ml according to the following schedule:

• First dose: Day 0.
• Second dose: 28 days after first dose.

Children from 2 months to <3 years of age: The primary vaccination series consists of two separate doses of 0.25 ml according to the following schedule:

• First dose: Day 0.
• Second dose: 28 days after first dose.

The vaccine should be administered by intramuscular injection into the deltoid muscle. In infants, the anterolateral aspect of the thigh may be used as injection site. Encephalitis Vaccine should never be injected intravascularly. When Encephalitis Vaccine is administered concomitantly with injectable vaccines, they should be given with separate syringes at opposite sites. Exceptionally, Encephalitis Vaccine can also be administered subcutaneously to patients with thrombocytopenia or bleeding disorders since bleeding may occur following an intramuscular administration. Subcutaneous administration could lead to a suboptimal response to the vaccine. However, it should be noted that there are no clinical efficacy data to support administration by the subcutaneous route.

Hypersensitivity to the active substance or to any of the excipients or to the residues protamine sulphate, formaldehyde, bovine serum albumin, host cell DNA, sodium metabisulphite, host cell protein. Individuals who show hypersensitivity reactions after receiving the first dose of the vaccine should not be given the second dose. Administration must be postponed in persons with acute severe febrile conditions.

Very common: headache, muscle pain, injection site pain, injection site tenderness, tiredness.

Common: Nausea, influenza like illness, fever, other injection site reactions (e.g. redness, hardening, swelling, itching).

Uncommon: vomiting, skin rash, changes in the lymph-nodes, migraine (throbbing headache, often accompanied by nausea and vomiting and sensitivity to light), dizziness, vertigo (spinning sensation), diarrhoea, belly pain, excessive sweating, itching, chills, general condition of feeling unwell, musculoskeletal stiffness, joint pain, weakness, abnormal laboratory liver test results (hepatic enzymes increased).

Pregnancy: There are limited amount of data from the use of Encephalitis Vaccine in pregnant women. In animal studies findings of unclear clinical relevance have been identified. As a precautionary measure, the use of Encephalitis Vaccine during pregnancy should be avoided.

Breast-feeding: It is unknown whether Encephalitis Vaccine is excreted in human milk. No effects on the breastfed newborn/infant are anticipated since the systemic exposure of the breast-feeding woman to Encephalitis Vaccine is negligible. However, in the absence of data and as a precautionary measure the use of Encephalitis Vaccine during lactation should be avoided.

Fertility: A study in rats did not indicate vaccine-related effects on female reproduction, foetal weight, survival and development of the off-spring.

Children below 2 months of age: The safety and efficacy of Encephalitis Vaccine in children younger than 2 months has not been established. No data are available.

Store in a refrigerator (2°C-8°C). Do not freeze. Store in the original package in order to protect from light.