Institute of Epidemiology and Health Statistics, School of Public Health, Lanzhou University, Lanzhou, Gansu 730000, China.
Gansu Provincial Center for Disease Control and Prevention, Lanzhou, Gansu 730000, China.
Acta Trop. 2022 Sep;233:106575. doi: 10.1016/j.actatropica.2022.106575. Epub 2022 Jun 26.
In 2008, Mainland China included the Japanese encephalitis (JE) vaccine in the Expanded Program on Immunization (EPI) to control the JE epidemic. However, Northwest China experienced the largest JE outbreak since 1994 in 2018, and the effects of the EPI in different regions are unclear. Therefore, we used an interrupted time series design to evaluate the effects of the EPI in different regions. In this study, β and β+β represented the slope or trend of the JE incidence before and after the EPI, respectively; β was the level change of the JE incidence immediately after the EPI; β represented the slope change of the JE incidence before and after the EPI. We found that the JE incidence in all regions showed a decreasing trend before the EPI (β<0.000, P<0.05). The JE incidence in Mainland China (β=-7.669, P<0.05), East China (β=-9.791, P<0.05), Central China (β=-10.695, P<0.05), South China (β=-6.551, P<0.05) and Southwest China (β=-2.216, P<0.05) decreased by 7.669/100,000, 9.791/100,000, 10.695/100,000, 6.551/100,000 and 2.216/100,000 immediately after the EPI, and the EPI had short-term effects on the JE incidence in these regions. The slope of the JE incidence in Mainland China (β=0.272, P<0.05), East China (β=0.337, P<0.05), Central China (β=0.381, P<0.05), South China (β=0.254, P<0.05) and Southwest China (β=0.081, P<0.05) increased by 0.272, 0.337, 0.381, 0.254 and 0.081 after the EPI, and the EPI had long-term effects on the JE incidence in these regions. The JE incidence in many regions (excluding North China) showed a decreasing trend after the EPI (β+β <0.000). Northwest China (GDP from 2008 to 2020 ranked last in Mainland China) and Southwest China (GDP from 2008 to 2020 ranked fifth in Mainland China), with underdeveloped economy, used to be low-epidemic regions of JE, but they have become high-epidemic regions in recent years. Economic development may contribute to the geographic variations in the effects of the EPI. Therefore, it is significant for JE control in Mainland China to increase support for underdeveloped regions and adjust the vaccine strategy according to the new epidemic situation of JE.
2008 年，中国大陆将乙型脑炎（JE）疫苗纳入扩大免疫规划（EPI）以控制 JE 流行。然而，2018 年西北地区经历了自 1994 年以来最大的 JE 疫情爆发，EPI 在不同地区的效果尚不清楚。因此，我们采用中断时间序列设计来评估 EPI 在不同地区的效果。在这项研究中，β和β+β分别代表 EPI 前后 JE 发病率的斜率或趋势；β是 EPI 后 JE 发病率的即时变化；β代表 EPI 前后 JE 发病率的斜率变化。我们发现，所有地区的 JE 发病率在 EPI 前均呈下降趋势（β<0.000，P<0.05）。中国大陆（β=-7.669，P<0.05）、华东（β=-9.791，P<0.05）、华中（β=-10.695，P<0.05）、华南（β=-6.551，P<0.05）和西南地区（β=-2.216，P<0.05）的 JE 发病率分别下降了 7.669/100,000、9.791/100,000、10.695/100,000、6.551/100,000 和 2.216/100,000，EPI 对这些地区的 JE 发病率有短期影响。中国大陆（β=0.272，P<0.05）、华东（β=0.337，P<0.05）、华中（β=0.381，P<0.05）、华南（β=0.254，P<0.05）和西南地区（β=0.081，P<0.05）的 JE 发病率斜率分别增加了 0.272、0.337、0.381、0.254 和 0.081，EPI 对这些地区的 JE 发病率有长期影响。EPI 后，许多地区（华北除外）的 JE 发病率呈下降趋势（β+β<0.000）。西北地区（2008 年至 2020 年 GDP 在中国内地排名最后）和西南地区（2008 年至 2020 年 GDP 在中国内地排名第五）经济欠发达，过去是 JE 的低流行区，但近年来已成为高流行区。经济发展可能是 EPI 效果地域差异的原因之一。因此，增加对欠发达地区的支持，根据 JE 的新疫情调整疫苗策略，对中国内地 JE 控制具有重要意义。
