Integrated Disease Surveillance Programme, State Surveillance Unit, West Bengal; National Institute of Cholera and Enteric Disease (NICED), Indian Council of Medical Research (ICMR), Kolkata, India.
Integrated Disease Surveillance Programme, State Surveillance Unit, West Bengal, India.
J Vector Borne Dis. 2021 Jul-Sep;58(3):199-205. doi: 10.4103/0972-9062.321751.
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.
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.
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.
日本脑炎（JE）是一种可通过疫苗预防的蚊媒虫媒病毒性疾病。印度西孟加拉邦卫生部门自 2006 年以来，在五个地区为 1 岁以下儿童启动了使用减毒活、单剂量 JE 疫苗（SA-14-14-2）的疫苗接种计划。其目的是比较接种和未接种地区急性脑炎综合征（AES）病例的样本阳性率（SPR），并观察接种地区三年内 SPR 和累积发病率的趋势。
该研究基于对监测数据的分析，包括来自该州所有 JE 检测机构的所有经测试的 AES 病例（包括在研究期间（2011-13 年）存在的 JE 确诊病例[IgM ELISA]）。计算累积发病率、95%置信区间的比值比（OR）、预防分数和卡方检验（用于 SPR）。采用线性回归评估发病率趋势。
在三年期间，五个接种地区贡献了 945 例 AES 和 88 例 JE 病例（SPR-9.3%），而 14 个未接种地区则贡献了 1807 例 AES 和 254 例 JE 病例（SPR-14.1%）。疫苗接种的效果明显，有利于接种地区的比值比逐渐下降。总体疫苗接种有效性为 68%，15 岁以下儿童为 80%[OR=0.20（0.10-0.41）]。在大多数接种地区，SPR 的趋势明显下降。
在大多数接种地区，SPR 在三年内显著下降，表明疫苗接种计划逐渐有效。
