Global Vaccine Safety

Mouse brain-derived Japanese encephalitis vaccine

Extract from report of GACVS meeting of 9-10 June 2005, published in the WHO Weekly Epidemiological Record on 15 July 2005

The Committee considered the decision taken by the Government of Japan on 30 May 2005 to suspend routine vaccination with the mouse brain-derived Japanese encephalitis (JE) vaccine currently used in Japan.3 This decision followed a review by the Japanese national advisory committee on vaccine adverse events of a single case of acute disseminated encephalomyelitis following JE vaccination and the national committee’s conclusion that it could not rule out a causal link with the vaccine. GACVS was advised that there is no definite evidence of an increased risk of acute disseminated encephalomyelitis temporally associated with JE vaccine and a causal link has not been demonstrated. The national authority recommends vaccination in high-risk areas only and for travel to endemic regions. The Japanese Government expects that the national recommendation for vaccination will be reconsidered when newer, possibly safer, inactivated JE vaccines become available. GACVS concluded, on the information presently available, that there is no good reason for WHO and national immunization programmes to change the current recommendations for JE vaccination for residents in and travellers to JE-endemic regions. The Committee will review the situation if further information becomes available.

3See (in Japanese).