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Two doses of an inactivated vaccine can help prevent Japanese encephalitis disease for at least one year; however, comparisons with other widely used vaccines are not available

Schiøler KL, Samuel M, Wai KL
Published Online: 
21 January 2009

Japanese encephalitis is a viral disease of the central nervous system with general symptoms of headache, fever, vomiting, and diarrhoea. Most people recover within a week without further complications, but approximately 1 in 300 suffers additional and severe symptoms such as disorientation, seizures, paralysis, and coma. Around thirty per cent of the severe cases are fatal and most survivors are left with serious and often chronic disabilities such as mental impairment, limb paralysis, and blindness. In this review of randomized controlled trials, a commercially available inactivated vaccine given in two doses was shown to provide disease protection for at least one year after vaccination, but with some adverse events. Disease protection by two vaccines, widely used in China but presently commercially unavailable, has not been investigated in randomized controlled trials. Further research is needed on all currently used as well as newly developed vaccines.