Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
1 mL vials
Approved indication: Japanese encephalitis prophylaxis
Australian Medicines Handbook Section 20.1
Japanese encephalitis is a flavivirus infection transmitted by mosquitoes. In epidemics, the immediate mortality rate can reach 50% and many survivors have neurological sequelae.1 The disease has been reported in many Asian countries and the vaccine is recommended for
- persons who will be resident in endemic areas for more than one month during the transmission season
- travellers who visit rural areas during epidemics
- tourists travelling extensively in rural areas known to have endemic disease.
This vaccine is an inactive vaccine produced from the brains of infected mice. Studies of mass immunisation in endemic countries show seroconversion in over 80% of vaccinees. The efficacy of preventing disease is 91% (95%, confidence interval 54-98%), but the duration of protection in unknown.
To protect at-risk travellers over the age of 12 months, 3 injections are needed. These injections are given subcutaneously over 30 days, with the last dose being given at least 10 days before travel. The vaccine is not recommended for everyone travelling to Asia, but it is appropriate to encourage all travellers to take precautions against mosquito bites.
Patients should be observed for 30 minutes after vaccination as angioedema or urticaria can occur within minutes. The risk of hypersensitivity is increased in patients with a history of allergy. As delayed reactions can occur, vaccinees should remain in an area with easy access to medical care for 10 days. The rate of serious allergic reactions ranges from 1-104 per 10 000 vaccinees. These adverse reactions are less common than local and systemic adverse effects which occur in 20% and 10% of vaccinees.
- Bucens M, O'Connor L. Japanese encephalitis and the traveller. Aust Fam Physician 1990;19:163-5.