A vaccine against Japanese encephalitis is available for people who are visiting a country where it is a risk. After a full course of the vaccine, you will have around 98% protection against Japanese encephalitis. This reduces to around 83% after 12 months.
For up-to-date information about which countries are considered high risk for Japanese encephalitis, check the NHS Fit for Travel website or the National Travel Health Network and Centre (NaTHNaC) website.
If you are travelling to a country where the vaccination is recommended, visit your GP or practice nurse at least six to eight weeks before you leave. They will discuss your trip with you and determine whether you should have the vaccination.
When is the vaccine recommended?
The Japanese encephalitis vaccine is recommended if:
- You are planning to spend a month or longer in a high-risk country during the rainy season.
- You are planning to visit any rural areas in high-risk countries, even if only for a short time.
- You will be taking part in any activities that may increase your risk of becoming infected, such as visiting rice fields or pig farms, cycling, camping or fieldwork.
The vaccine
Two vaccines for Japanese encephalitis are currently available in the UK:
Both vaccines are given as a course of injections. Ideally, this should be completed at least one month before you travel. This gives enough time for your body to develop full immunity (resistance to the virus).
IXIARO is given as two injections, with the second dose given 28 days after the first. A booster dose is required after 12 months. This vaccine is suitable for people who are 18 years of age and over.
Green Cross is given as three injections. The second dose is given seven days after the first, and the third dose is given 28 days after the first. A booster dose is required after 12 months, then once a year if you are still at risk of catching Japanese encephalitis. This vaccine is suitable for children who are over one year of age.
The Green Cross vaccine must be completed at least 10 days before you travel because an allergic reaction to the vaccine can take this long to show up.
After each injection, you will be monitored for 30 minutes to check for any side effects (see below).
Rapid course
If there is not enough time before you travel to complete a full course as described above, you may be able to have a rapid course of the vaccination.
You can receive three doses of the Green Cross vaccine with seven days between each dose, or you can receive two doses seven days apart with a booster dose three months later.
The two dose rapid course of the Green Cross vaccine will provide less protection than the three dose course. These will still need to be completed at least 10 days before you leave in case you have a reaction.
Side effects
Some people get side effects after having the vaccine. Between 10% and 20% of people may experience:
- soreness, redness or swelling at the site of the injection
- a high temperature of 38C (100.4F) or over
- dizziness
- headache
- feeling sick
- vomiting
- abdominal pain
- aching muscles
More serious side effects occur in around 0.6% of people. These include:
- urticaria or hives (a raised, itchy red rash)
- swelling of the face
- difficulty breathing
This type of reaction usually occurs within minutes of having the vaccine, although it could appear up to two weeks later.
If you have any of these symptoms, see your GP immediately or call NHS Direct on 0845 4647.
If you have the vaccine while you are travelling abroad, stay in an area where you have access to a doctor or hospital for at least 10 days in case you have a bad reaction.
When is the vaccine not recommended?
The Japanese encephalitis vaccine is not suitable for children under one year of age.
If you have previously had a severe allergic reaction (anaphylaxis) to a Japanese encephalitis vaccine or are allergic to any of the ingredients in the vaccine, do not have it.
You may be more at risk of having an adverse reaction to the vaccine if:
- You have other allergies, such as allergic rhinitis or asthma.
- You have a condition that affects your nervous system (your brain, spinal cord and nerves) such as multiple sclerosis.
- You have had convulsions (fits) in the previous year.
In all cases, the risks of catching the Japanese encephalitis virus will be weighed up against the risks of having an adverse reaction to the vaccine.
