应急接种等措施在一起流行性腮腺炎暴发疫情防控中的效果评价

Evaluation on the effect of emergency inoculation and other prevention and control measures during an outbreak of epidemic mumps

目的评价应急接种等措施在一起流行性腮腺炎暴发疫情防控中的效果。方法根据病例定义收集该起暴发疫情中的所有病例发病、隔离日期,疫情中采取的应急接种、病例隔离、停课、洗手宣传教育等防控措施信息,计算应急接种的疫苗保护效率(vaccine efficiency,VE),采用离散时间模型对拟合实际暴发疫情数据计算传播能力,计算应急接种、病例隔离、停课和洗手的效果指数。结果该起暴发疫情共调查共1471人,发生4代病例,三代间距均为15d;暴发期间共339人接种了麻腮风疫苗,应急接种率为73.38%,发病3人,罹患率0.88%。未应急接种的人数为123人,发病25人,罹患率20.33%。应急接种的疫苗保护效率为95.6%。隔离在第二至第四代的效果系数分别为0.43、0.46和0.47;停课和洗手联合措施在第二、三代病例发生时产生了作用,效果系数分别为0.279和0.078。模型模拟结果显示,接种率达到90%~100%,罹患率、疫情持续时间、疫情高峰出现周才能产生明显防控效果。结论在流腮暴发疫情中,应急接种率达到90%~100%才能起到好的防控效果;停课和洗手等健康教育能起到一定作用,但主要防控措施应为高接种率和及时病例隔离。

Objective To evaluate the efficacy of emergency inoculation and other prevention and control measures during an outbreak of epidemic mumps. Methods According to the case definition, we collected the data of all cases in this outbreak, including illness onset date, case isolation date, returning to school date, emergency vaccination date and times, school closure date and interval and health education like hand-washing. The vaccine efficacy (VE) of emergency vaccination was calculated. A discrete-time model was employed to simulate the transmissibility and effectiveness of the measures, including the proportion of isolation and effectiveness indexes of emergency vaccination, case isolation, school closure and hand-washing.Results A total of 1,471 students were surveyed in this outbreak. The outbreak experienced 4 generations of cases, with an average interval of 15 days. Altogether 339 students received measles-mumps-rubella vaccine during the outbreak, and the emergency inoculation rate was 73.38%. 3 students were infected with mumps, with the attack rate of 0.88%. 123 students did not receive the emergency inoculation, 25 students were infected with mumps, with the attack rate of 20.33%. The VE of the emergency inoculation was 95.6%. The effectiveness indexes of isolation in the 2rd-4th generations of cases were 0.43, 0.46 and 0.47 respectively. School closure and hand-washing became effective in the 2nd-3rd generations of cases, with the effectiveness indexes of 0.279 and 0.078 respectively. According to the simulation results of the model, there would become effective in total attack rate, duration of outbreak and epidemic peak week while the emergency inoculation rate was up to 90%-100%. Conclusions There will not be obvious effect in mumps outbreak unless the emergency inoculation rate runs up to 90%-100%. Health education like school closure and hand-washing can make some effects, but a high vaccination rate and timely isolation of cases should be considered as the primary prevention and control measures.