Department of Epidemiology, University of Michigan, School of Public Health.
Department of Microbiology and Immunology Department of Internal Medicine, Division of Infectious Diseases, University of Michigan, Ann Arbor.
Clin Infect Dis. 2016 Oct 15;63(8):1017-25. doi: 10.1093/cid/ciw432. Epub 2016 Jul 1.
The 2014-2015 influenza season was severe, with circulating influenza A (H3N2) viruses that were antigenically drifted from the vaccine virus. Reported vaccine effectiveness (VE) estimates from ambulatory care settings were markedly decreased.
Adults, hospitalized at 2 hospitals in southeast Michigan for acute respiratory illnesses, defined by admission diagnoses, of ≤10 days duration were prospectively enrolled. Throat and nasal swab specimens were collected, combined, and tested for influenza by real-time reverse transcription polymerase chain reaction. VE was estimated by comparing the vaccination status of those testing positive for influenza with those testing negative in logistic regression models adjusted for age, sex, hospital, calendar time, time from illness onset to specimen collection, frailty score, and Charlson comorbidity index (CCI).
Among 624 patients included in the analysis, 421 (68%) were vaccinated, 337 (54%) were female, 220 (35%) were age ≥65 years, and 92% had CCI > 0, indicating ≥1 comorbid conditions. Ninety-eight (16%) patients tested positive for influenza A (H3N2); among 60 (61%) A (H3N2) viruses tested by pyrosequencing, 53 (88%) belonged to the drifted 3C.2a genetic group. Adjusted VE was 43% (95% confidence interval [CI], 4-67) against influenza A (H3N2); 40% (95% CI, -13 to 68) for those <65 years, and 48% (95% CI, -33 to 80) for those ≥65 years. Sensitivity analyses largely supported these estimates.
VE estimates appeared higher than reports from similar studies in ambulatory care settings, suggesting that the 2014-2015 vaccine may have been more effective in preventing severe illness requiring hospitalization.
2014-2015 年流感季节较为严重，流行的甲型 H3N2 流感病毒与疫苗病毒发生抗原漂移。来自门诊的报告疫苗有效率（VE）估计明显下降。
东南密歇根州的 2 家医院住院的急性呼吸道疾病患者，通过入院诊断定义为病程≤10 天，前瞻性纳入研究。采集咽喉和鼻腔拭子标本，混合后通过实时逆转录聚合酶链反应检测流感。通过比较流感检测阳性者和阴性者的疫苗接种情况，用逻辑回归模型进行 VE 估计，调整因素包括年龄、性别、医院、日历时间、发病到标本采集的时间、虚弱评分和 Charlson 合并症指数（CCI）。
在 624 例纳入分析的患者中，421 例（68%）接种过疫苗，337 例（54%）为女性，220 例（35%）年龄≥65 岁，92%的患者 CCI>0，表明有≥1 种合并症。98 例（16%）患者流感 A（H3N2）检测阳性；通过焦磷酸测序检测 60 例 A（H3N2）病毒中，53 例（88%）属于漂移的 3C.2a 基因群。调整 VE 为 43%（95%置信区间 [CI]，4-67），预防流感 A（H3N2）；<65 岁者为 40%（95% CI，-13 至 68），≥65 岁者为 48%（95% CI，-33 至 80）。敏感性分析基本支持这些估计值。
VE 估计值高于门诊类似研究的报告，表明 2014-2015 年疫苗可能更能有效预防需要住院的严重疾病。
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