The Japanese encephalitis virus (JEV) is endemic in many countries in southern Asia and the western Pacific Rim, with new spread to previously unrecognized countries. It is an important cause of childhood neurological disease associated with permanent neurological sequelae and death. Fortunately, JE is a
vaccine-preventable disease. The ChimeriVax™-JE (Sanofi Pasteur, Lyon, France) is a live-attenuated chimeric
vaccine derived from the live-attenuated yellow fever virus, YF17D, which expresses the envelope
proteins of the attenuated JEV
vaccine strain, SA14-14-2. It is a safe, well-tolerated
vaccine that is highly immunogenic in adults and children. The average geometric mean
neutralizing antibody titer (GMT) in adults is 1,392 and over 90% of adults remain seroprotected 5 years after vaccination. In children and toddlers, more than 80% remain seroprotected 2 years after primary vaccination and demonstrate a robust and durable anamnestic response (>500-fold rise in GMT) with 99.1% seroprotection rates 1 year after a booster
vaccine dose. The ChimeriVax™-JE is effective in children living in endemic regions where the
vaccine could possibly be integrated into existing childhood vaccination programs. ChimeriVax™-JE is also indicated for travelers at risk of JE
infection.