JAPANESE ENCEPHALITIS VACCINE



Indications

– Prevention of Japanese encephalitis:
• in children from 1 year and adults in endemic countries (rural areas of Southeast and Southwest Asia and Western Pacific countries)
• in travellers spending more than 1 month in endemic countries, in rural areas and during the wet season

Composition, forms, route of administration

– Inactivated virus vaccine
– Powder for injection in single-dose vial, to be dissolved with the entire vial of the diluent supplied by the manufacturer, for SC injection

Dosage

– Child from 1 to 3 years: 0.5 ml per dose
– Child over 3 years and adult: 1 ml per dose

There are several vaccination schedules. For information, for travellers:
3 doses on Day 0, Day 7 and Day 28; a booster dose every 3 years if risk persists.

An accelerated schedule is possible (3 doses on Day 0, Day 7 and Day 14) but this is likely to result in lower antibody levels than the standard schedule.
The 3rd dose should be given at least 10 days before departure to ensure an adequate immune response and access to medical care in the event of adverse reactions.

Contra-indications, adverse effects, precautions

– Do not administer to patients with history of an allergic reaction to a previous injection of Japanese encephalitis vaccine.
– Vaccination should be postponed in the event of severe acute febrile illness; minor infections are not contra-indications.
– May cause:
• redness and swelling at the injection site;
• fever, headache, chills, asthenia;
• hypersensitivity reactions (urticaria, angioedema), immediate or delayed (up to 2 weeks after injection);
• rarely: encephalitis, encephalopathy.
– Do not mix with other vaccines in the same syringe (inactivation of vaccines).
– If administered simultaneously with EPI vaccines, use different syringes and injection sites.
– Pregnancy: only administer if there is a high risk of contamination.
– Breast-feeding: no contra-indication

Remarks

– Protection lasts at least 2 years after 3 doses.
– Caution: there are different vaccines against EJ, with different dosages and administration schedules (e.g. suspension for injection in pre-filled syringe, administered in 2 doses (0.5 ml on D0 and D28) in adults, by IM route). For each vaccine, follow manufacturer's instructions.
– Storage
• Powder: between 2 °C and 8 °C. Do not freeze.
• 
Diluent: a cold chain is not required for storage. However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2 °C and 8 °C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce vaccine efficacy. Do not freeze.
• 
Reconstituted vaccine: between 2 °C and 8 °C, for 6 hours maximum.