How serious is Japanese encephalitis?
Japanese encephalitis (JE) is a mosquito-borne viral infection that can inflame the brain. It is rare in British travellers.
The Green Book reports:
Approximately 1 in 250 infections causes severe illness.
Among symptomatic cases, the death rate can reach 30%.
20–30% of survivors experience permanent problems, including difficulties with learning, behaviour, movement or seizures.
These figures describe outcomes following infection—not your chance of catching it on holiday. Most infections are mild or symptom-free.
How does the vaccine work?
IXIARO contains inactivated virus, so it cannot cause JE. It also contains aluminium hydroxide, an adjuvant that improves the immune response.
Why two doses?
The recommended initial course requires two injections. Protection takes up to one week after the second dose to develop.
The Green Book does not provide a percentage comparing protection after one IXIARO dose versus two.
When should I book?
The standard doses are 28 days apart. A licensed faster schedule uses days 0 and 7 for adults aged 18–64. Finish ideally one week before exposure.
Who needs it?
Assessment considers destination, season, duration and activities. Rural stays, rice fields and pig farms can increase risk. There is no specific treatment for JE; care is supportive.
Discuss your trip with Trustwell Clinic
A recommendation should reflect your actual plans. Contact Trustwell Clinic with your itinerary and departure date so we can discuss whether vaccination is appropriate and plan your appointments.
Clinical information: UK Green Book, Chapter 20: Japanese encephalitis, February 2024.