Effectiveness of introduction of JEV vaccination into routine immunization program in a tribal district of Odisha.

Background: A severe outbreak of Japanese encephalitis (JE) and acute encephalitis syndrome (AES) with high case fatality among tribal children was reported from Malkangiri district of Odisha, during September to November 2016 affecting 336 children with 103 deaths. Following the outbreak, a mass vaccination campaign was introduced in Malkangiri district in2017. In 2018, the JE vaccine was introduced into the routine immunization program as per National Immunization Schedule. Our study surveys the JE vaccination coverage among children of Malkangiri and the incidence of JE cases for a period of three years. Methodology: The current study was conducted by establishing prospective and retrospective AES surveillance system and household vaccine coverage surveys in Malkangiri district. In the target population, the vaccination coverage survey was undertaken and also additional immunization coverage data from sub-centers was collected. Results: After 2016 JE outbreak, a mass vaccination campaign was carried out in children up to 15 years of age, where 96% of children were covered in the district in 2017 and only four AES cases were detected. Under routine immunization program, the vaccine coverage for the year 2018 was 68% for JE-1 dose and 37% for JE-2 dose. There were 8 AES cases detected in 2018 out of which four children died. Vaccination coverage for 2019 was 97% for JE-1 dose and 84% for JE-2 dose. The AES cases detected in 2019 was nil. Conclusion: Vaccination against JEV and AES surveillance systems has an important role in prevention and control of AES outbreaks.