Cartter M L, Renzullo P O, Helgerson S D, Martin S M, Jekel J F
Division of Field Services, Centers for Disease Control, Atlanta, Georgia.
Infect Control Hosp Epidemiol. 1990 Sep;11(9):473-8. doi: 10.1086/646214.
During the 1984-1985 influenza season, outbreaks of influenza A (H3N2) occurred in three Connecticut nursing homes. Influenza vaccination rates were 67% (96 out of 144), 35% (30 out of 85) and 69% (332 out of 483), respectively. The relative risk of illness for vaccinated compared to unvaccinated residents was 1.8 (95% confidence interval, 0.6, 5.9), 1.6 (95% confidence interval, 0.8, 3.0) and 1.1 (95% confidence interval, 0.8, 1.7) for each of the three nursing homes, respectively. In the third outbreak, 22 vaccinated residents without clinical illness had a geometric mean titer of hemagglutination-inhibition (HI) antibody of 20. Although low, this titer was significantly higher than that of nine unvaccinated residents without clinical illness (12, p less than .05); only three (14%) vaccinated residents had HI titers of greater than or equal to 40. These results suggest that levels of HI antibody in vaccinated residents were not protective at the time of the third outbreak, four to five months after vaccination. In general, the study of vaccine effectiveness in nursing homes is limited by sample size and statistical power. Despite these limits, the retrospective investigation of influenza outbreaks in nursing homes is often the only practical way to evaluate influenza vaccine effectiveness in the elderly on a yearly basis.
在1984 - 1985年流感季节期间，康涅狄格州的三家疗养院爆发了甲型（H3N2）流感。流感疫苗接种率分别为67%（144人中有96人）、35%（85人中有30人）和69%（483人中有332人）。三家疗养院中，接种疫苗的居民与未接种疫苗的居民相比，患病的相对风险分别为1.8（95%置信区间为0.6, 5.9）、1.6（95%置信区间为0.8, 3.0）和1.1（95%置信区间为0.8, 1.7）。在第三次疫情爆发中，22名无临床症状的接种疫苗居民的血凝抑制（HI）抗体几何平均滴度为20。尽管该滴度较低，但显著高于9名无临床症状的未接种疫苗居民（12，p小于0.05）；只有3名（14%）接种疫苗居民的HI滴度大于或等于40。这些结果表明，在第三次疫情爆发时，即接种疫苗四至五个月后，接种疫苗居民体内的HI抗体水平没有起到保护作用。一般来说，疗养院中疫苗有效性的研究受到样本量和统计效力的限制。尽管有这些限制，但对疗养院流感疫情的回顾性调查往往是每年评估老年人流感疫苗有效性的唯一可行方法。
