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Immunizations - travel vaccinations - Management
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Definition
- Japanese encephalitis is caused by a flavivirus that is spread by the bite of infected mosquitoes. Illness ranges from asymptomatic infection to severe encephalitis with a high mortality rate and a high risk of permanent neurological sequelae.
When is Japanese encephalitis vaccine indicated?
- Japanese encephalitis vaccine may be recommended for:
- Travellers to south east Asia, Indian subcontinent, the Far East and tropical north east Australia (if staying for a month or longer in endemic areas during the transmission season, especially if travel will include rural areas).
- Travellers with shorter exposure periods if the risk is considered sufficient, such as those spending a short period of time in rice fields (where the mosquito vector breeds) or close to pig farming (a reservoir host for the virus).
- Country-specific recommendations and information on the global epidemiology of Japanese encephalitis can be found in the 'Yellow Book', Health information for overseas travel.
In depth
What types of Japanese encephalitis vaccine are available?
- There are two inactivated vaccines currently available for Japanese encephalitis:
- IXIARO®
- Licensed in the UK for adults over 18 years of age.
- IXIARO® is currently not recommended for use in young children, however it can be considered for off-label use in older teenagers.
- Black triangle: still under intensive post-marketing surveillance by the Medicines and Healthcare products Regulatory Agency (MHRA).
- Green Cross®
- Unlicensed in the UK; only available on a named-patient basis.
- Recommended for children over of 1 year of age; not recommended for use in adults (licensed alternative available).
- JE-VAX® is no longer available.
In depth
What schedule is used for Japanese encephalitis vaccine?
- Ideally, complete the vaccine schedule a month before travel (to allow immunity to develop).
- The Green Cross® vaccine should be completed at least 10 days prior to departure (to allow for observation for delayed allergic reactions). People should be warned of the possibility of delayed anaphylactic reactions.
- This is not necessary for the IXIARO® vaccine.
- Observe all recipients for 30 minutes (to check for urticaria, angio-oedema, and cardiovascular collapse). Full resuscitation facilities should be present.
Table 1. Schedule for Japanese encephalitis vaccine.
Vaccine | Schedule | Length of protection | Age range |
|---|
IXIARO® | 2 doses: Day 0 and 28. | Boost at 12 months following the primary course, if at continued risk. | From 18 years |
Green Cross® | 3 doses: Day 0, 7, and 28. | Boost at 12 months following primary course, then every 3 years unless at particular risk in which case annual boosters are recommended. | From 1 year Children under 3 years should receive 0.5 mL of vaccine |
|
In depth
Can I use a rapid schedule for Japanese encephalitis vaccine?
- A rapid schedule of 3 doses of Green Cross® vaccine, given on days 0, 7, and 14 can be used.
- Alternatively, a rapid schedule of 2 doses of Green Cross® vaccine given one week apart can be used (but there is less immune response than if 3 doses of vaccine are given). Give a booster dose 3 months later.
- Complete the vaccine schedule at least 10 days prior to departure (to allow for observation for delayed allergic reactions), and ideally a month before travel (to allow immunity to develop).
In depth
What are the adverse effects of Japanese encephalitis vaccine?
- Tenderness, redness, and swelling have been reported in about 20% of vaccinated people. Fever, headache, malaise, chills, dizziness, nausea, vomiting, and abdominal pain have been reported in 10% of recipients.
- Local and mild systemic adverse effects occur in 10–20% of recipients.
- Serious systemic reactions (urticaria, angio-oedema, and cardiovascular collapse), occur in about 0.6% of vaccine recipients. Most occur within the first few minutes of vaccination, but may occur up to 2 weeks after vaccination with the Green Cross vaccine.
In depth
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