Indications
This vaccine protects against Japanese encephalitis, a viral infection of the brain spread by mosquito bites in rural and farming areas of South and East Asia, including Bangladesh. Most infections are mild, but a small number cause brain swelling (encephalitis) that can lead to seizures, lasting disability or death. The vaccine is used for people living in or travelling to areas where the disease occurs, usually from 9 months of age.
How It Works
The product described here is a live, weakened (attenuated) vaccine made by placing genes from the Japanese encephalitis virus into a harmless yellow fever vaccine virus. It multiplies only a little in the body and teaches the immune system to make antibodies and immune cells that recognise the real virus, giving long lasting protection.
Dosage and Administration
It is given as an injection under the skin by a doctor, nurse or trained vaccinator. The number of doses, including whether a booster is needed for children, follows the schedule set by the doctor or the national programme. Travellers should ideally complete vaccination at least 2 weeks before possible exposure.
Interactions
- Medicines that weaken the immune system, such as high dose Prednisolone, chemotherapy or Methotrexate, may make the live vaccine unsafe or less effective.
- Immunoglobulins or blood products given in the months before may reduce the response; the doctor will advise timing.
- Other live vaccines are usually given on the same day or at least 4 weeks apart.
Contraindications
- Severe allergic reaction to a previous dose or to any vaccine component.
- Weakened immune system, for example from HIV with low CD4 count, cancer treatment, high dose steroids or other immunosuppressive treatment, or inherited immune deficiency.
- Pregnancy.
- Breastfeeding, as a precaution.
- High fever or acute illness (vaccination is delayed).
Side Effects
Common: pain, redness or swelling at the injection site, headache, tiredness, muscle aches, mild fever and, in children, irritability or loss of appetite, usually lasting 1 to 3 days. Rare: severe allergic reaction. Very rare serious nervous system or organ reactions have been described with live vaccines of this type.
Get urgent medical help if there is difficulty breathing, swelling of the face or throat, a seizure, severe headache with stiff neck, confusion, unusual drowsiness, or weakness of the limbs after vaccination.
Pregnancy and Lactation
It is a live vaccine and must not be given during pregnancy. Women should avoid becoming pregnant for 4 weeks after vaccination. It is not recommended during breastfeeding; a non live (inactivated) vaccine may be considered if protection is needed.
Precautions and Warnings
Tell the vaccinator about any illness, allergies, immune problems, medicines, pregnancy or breastfeeding, and any reaction to a yellow fever vaccine. The vaccinated person should be watched for 15 to 30 minutes afterwards. Vaccination does not protect everyone, so mosquito bite prevention (nets, repellents, long sleeves) is still important.
Overdose
Overdose is unlikely because it is given by health professionals as a single measured dose. If an extra dose is given by mistake, inform the doctor.
Therapeutic Class
Viral vaccine, live attenuated (Japanese encephalitis)
Storage
Store in a refrigerator at 2 to 8°C. Do not freeze. Protect from light. Use promptly after reconstitution, as directed on the pack. Usually kept by the clinic or pharmacy.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.