Live and Inactivated Japanese Encephalitis Vaccine Interchangeability in Travelers: Review of Evidence and Recommendation to Travelers

Abstract

Japanese encephalitis (JE) is a vector borne zoonotic disease caused by the virus belongs to Flaviviridae family. Japanese encephalitis virus is known as a major etiological agent of encephalitis in Asia, few western pacific nations and in northern Australia. JE has case fatality rate of 20-30% and 30-50% of the survivors have neurological sequalae. It is estimated that’s almost 67,900 cases occur annually, and overall incidence is 1.8 per 100000. There is no treatment available for JE and it cause significant mortality and morbidity in infected people. JE can be prevented by using vaccines. Different types of vaccines like mouse brain derived inactivated vaccine (MBJEVs), inactivated primary hamster kidney cells (PHK) derived vaccine, live attenuated SA14-14-2 virus, and chimeric live attenuated JE vaccine (ChimeriVax, JE-CV). Vaccination against JE has been carried out extensively in Asian countries from past few decades. JE vaccines are highly recommended for travellers to the endemic regions, this gives to the rise of the question of Interchangeability of JE vaccines.  Interchangeability of inactivated, live and chimeric JE vaccines has been studied in different regions. According to all these case studies discussed in the review it is possible to interchange JE vaccine because after booster dose they gave significant Sero-protection in terms of geometric mean titer GMTs and plaque reduction neutralizing test PRNT against JE virus. But present data is limited and further large-scale studies are recommended.