Encephalitis Vaccine

Imojev is indicated for active immunisation against Japanese encephalitis in adults, adolescents, children and infants aged 2 months and older. Imojev 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.