Foster D A, Talsma A, Furumoto-Dawson A, Ohmit S E, Margulies J R, Arden N H, Monto A S
Department of Epidemiology, School of Public Health I, University of Michigan, Ann Arbor 48109-2029.
Am J Epidemiol. 1992 Aug 1;136(3):296-307. doi: 10.1093/oxfordjournals.aje.a116495.
During the winter of 1989-1990, influenza type A(H3N2) circulated widely, causing excess morbidity and mortality nationwide. From November through April, 1989-1990, hospitalized cases of pneumonia and influenza occurring among noninstitutionalized individuals 65 or more years of age were identified by 20 acute care hospitals in southern lower Michigan. These cases were group matched on age, sex, race, and zip code to randomly sampled, community-based controls from a comprehensive listing of Medicare beneficiaries residing in the study area. Self-reported data were collected from cases and controls on influenza vaccine status for the 1989-1990 season and on a number of other factors which could have influenced vaccination status or outcome. Questionnaires were completed by 1,907 individuals, 449 of whom were cases, resulting in an overall response rate of 76%. A community-based influenza surveillance system was implemented to determine the timing and intensity of viral activity and influenza-like illness. Vaccine effectiveness in preventing overall pneumonia and influenza hospitalizations was estimated by logistic regression. During the 3-month period of surveillance-confirmed peak influenza type A(H3N2) circulation, vaccine effectiveness was 45% (95% confidence interval 14-64, p = 0.009). However, during the 3-month period of low or absent virus activity, identical methodology and model specification resulted in an effectiveness estimate of 21% that was not statistically different from zero (p = 0.36). The effectiveness determined during the peak period of virus circulation is felt to be a conservative estimate, since agents other than influenza are responsible for pneumonia and influenza hospitalizations, even during times of peak influenza activity.
1989 - 1990年冬季，甲型（H3N2）流感病毒广泛传播，在全国范围内导致发病率和死亡率上升。1989年11月至1990年4月期间，密歇根州南部下游地区的20家急症医院确定了65岁及以上非机构化个体中发生的肺炎和流感住院病例。这些病例按照年龄、性别、种族和邮政编码与从居住在研究区域的医疗保险受益人的综合列表中随机抽取的社区对照进行匹配。收集了病例和对照关于1989 - 1990年流感季节流感疫苗接种状况以及其他一些可能影响接种状况或结果的因素的自我报告数据。1907人完成了问卷调查，其中449人为病例，总体回复率为76%。实施了基于社区的流感监测系统以确定病毒活动和流感样疾病的时间和强度。通过逻辑回归估计疫苗预防总体肺炎和流感住院的有效性。在监测确认的甲型（H3N2）流感病毒传播高峰期的3个月期间，疫苗有效性为45%（95%置信区间14 - 64，p = 0.009）。然而，在病毒活动低或无病毒活动的3个月期间，相同的方法和模型设定得出的有效性估计为21%，与零无统计学差异（p = 0.36）。在病毒传播高峰期确定的有效性被认为是保守估计，因为即使在流感活动高峰期，除流感外其他病原体也可导致肺炎和流感住院。
