Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor.
Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland.
Clin Infect Dis. 2017 Oct 30;65(10):1644-1651. doi: 10.1093/cid/cix608.
Antigenically drifted A(H3N2) viruses circulated extensively during the 2014-2015 influenza season. Vaccine effectiveness (VE) was low and not significant among outpatients but in a hospitalized population was 43%. At least one study paradoxically observed increased A(H3N2) infection among those vaccinated 3 consecutive years.
We followed a cohort of 1341 individuals from 340 households. VE against laboratory-confirmed influenza was estimated. Hemagglutination-inhibition and neuraminidase-inhibition antibody titers were determined in subjects ≥13 years.
Influenza A(H3N2) was identified in 166 (12%) individuals and B(Yamagata) in 34 (2%). VE against A(H3N2) was -3% (95% confidence interval [CI]: -55%, 32%) and similarly ineffective between age groups; increased risk of infection was not observed among those vaccinated in 2 or 3 previous years. VE against influenza B(Yamagata) was 57% (95% CI: -3%, 82%) but only significantly protective in children <9 years (87% [95% CI: 43%, 97%]). Less than 20% of older children and adults had ≥4-fold antibody titer rise against influenza A(H3N2) and B antigens following vaccination; responses were surprisingly similar for antigens included in the vaccine and those similar to circulating viruses. Antibody against A/Hong Kong/4801/14, similar to circulating 2014-2015 A(H3N2) viruses and included in the 2016-2017 vaccine, did not significantly predict protection.
Absence of VE against A(H3N2) was consistent with circulation of antigenically drifted viruses; however, generally limited antibody response following vaccination is concerning even in the context of antigenic mismatch. Although 2014-2015 vaccines were not effective in preventing A(H3N2) infection, no increased susceptibility was detected among the repeatedly vaccinated.
在 2014-2015 年流感季节，抗原漂移的 A(H3N2) 病毒广泛传播。疫苗效力（VE）在门诊患者中较低且无统计学意义，但在住院人群中为 43%。至少有一项研究观察到，连续 3 年接种疫苗的人群中 A(H3N2) 感染增加，这一结果令人费解。
我们对 340 户家庭的 1341 名个体进行了随访。估计了针对实验室确诊流感的 VE。≥13 岁的受试者测定血凝抑制和神经氨酸酶抑制抗体滴度。
166 名（12%）个体和 34 名（2%）个体鉴定出 A(H3N2) 和 B(Yamagata)。针对 A(H3N2)的 VE 为-3%（95%置信区间[CI]：-55%，32%），且在不同年龄组之间效果相似；在过去 2 或 3 年接种疫苗的人群中未观察到感染风险增加。针对 B(Yamagata)的 VE 为 57%（95% CI：-3%，82%），但仅在<9 岁儿童中具有显著保护作用（87%[95% CI：43%，97%]）。<9 岁的较大儿童和成年人中，接种疫苗后针对流感 A(H3N2)和 B 抗原的抗体滴度升高<4 倍的不到 20%；针对疫苗中包含的抗原和与循环病毒相似的抗原的反应出人意料地相似。针对 A/Hong Kong/4801/14 的抗体与循环的 2014-2015 年 A(H3N2)病毒相似，包含在 2016-2017 年疫苗中，但并未显著预测保护作用。
针对 A(H3N2)的 VE 缺失与抗原漂移病毒的流行一致；然而，即使在抗原不匹配的情况下，接种疫苗后通常有限的抗体反应也令人担忧。尽管 2014-2015 年的疫苗不能有效预防 A(H3N2)感染，但在反复接种疫苗的人群中未检测到易感性增加。
