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Assessment of effectiveness of Japanese encephalitis vaccination in West Bengal, India using sample positivity rate as an alternate measure

Assessment of effectiveness of Japanese encephalitis vaccination in West Bengal, India using sample positivity rate as an alternate measure

Authors :
Debjit Chakraborty
Surajita Banerjee
Dipankar Maji
Tushar Kanti Dey
Kulothungan Vaitheeswaran
Palash Mondal
Prashanta Biswas
Falguni Debnath
Pranab Chatterjee
Source :
Journal of Vector Borne Diseases, Vol 58, Iss 3, Pp 199-205 (2021)
Publication Year :
2021
Publisher :
Wolters Kluwer Medknow Publications, 2021.

Abstract

Background & objectives: Japanese encephalitis (JE), is a vaccine preventable mosquito borne arboviral disease. The State Health Department of West Bengal, India started a vaccination programme using live attenuated, single dose JE vaccine (SA-14-14-2) in children aged 1-below15 years since 2006 in five districts. The objectives were to compare Sample Positivity Rates (SPR) of Acute Encephalitis Syndrome (AES) cases for JE between vaccinated & unvaccinated districts and observe trend of SPR & Cumulative Incidence in vaccinated districts for three years. Methods: The study was based on the analysis of surveillance data from all tested AES cases including confirmed JE (IgM ELISA) from all JE testing facilities existent in the state during the study period (2011–13). Calculation of Cumulative Incidence, Odds Ratio (OR) with 95% CI, Preventive Fraction and Chi Square for trend (for SPR) was done. Trend of incidence was assessed by linear regression. Results: In three years, 5 vaccinated districts contributed 945 AES and 88 JE cases (SPR - 9.3%) compared to 1807 and 254 (SPR - 14.1%) JE cases in 14 unvaccinated districts. Effectiveness of vaccination was evident by gradual decline of Odds Ratio in favour of vaccinated districts. Vaccination effectiveness of 68% overall and 80% [OR = 0.20 (0.10 - 0.41)] in below 15 years were observed. Trend of SPR was found significantly declining in most of the vaccinated districts. Interpretation & conclusion: Significant reduction in sample positivity rate over three years in most of the vaccinated districts indicated that the vaccination programme had been gradually effective.

Details

Language :
English
ISSN :
09729062
Volume :
58
Issue :
3
Database :
Directory of Open Access Journals
Journal :
Journal of Vector Borne Diseases
Publication Type :
Academic Journal
Accession number :
edsdoj.f60edd202c249faa12e4b1e55685ae0
Document Type :
article
Full Text :
https://doi.org/10.4103/0972-9062.321751