Background Hemagglutinin (HA)-inhibiting antibodies contribute to the immune defense against influenza infection. However, there are insufficient data on the extent of correlation between vaccine-elicited HA antibodies and protection in children against different influenza strains, particularly when comparing live attenuated influenza vaccines (LAIV) versus inactivated influenza vaccines (IIV). Methods We measured postvaccination hemagglutination-inhibition (HAI) titers in 3–15-year-old participants of a cluster-randomized controlled trial of trivalent LAIV(3) versus IIV(3) in Canadian Hutterite colonies. We assessed HAI titers as predictors of symptomatic, reverse transcription polymerase chain reaction (RT-PCR)-confirmed influenza over 3 influenza seasons using Cox proportional hazards regression models with vaccine type as a covariate. Results For each log2 unit increase in postvaccination HAI against A/H1N1 in 2013–2014, A/H3N2 2014–2015, and B/Yamagata in 2013–2014 (each the predominant circulating strain for the respective influenza season), the reduction in the risk of confirmed influenza was equal to 29.6% (95% confidence interval [CI], 17.1%–39.5%), 34.8% (95% CI, 17.2%–47.9%), and 31.8% (95% CI, 23.8%–38.5%), respectively. No reduction in the risk of influenza was observed with B/Yamagata-specific HAI titers in 2012–2013, which was dominated by a mixture of Yamagata and Victoria strains. Despite the overall lower HAI titers in the LAIV3 group, both H1N1 and H3N2 HAI titers were associated with protection against subtype matched influenza. Conclusions Both LAIV3- and IIV3-elicited HA antibodies are associated with protection against influenza infection in seasons when the vaccine strains match the circulating influenza strain subtypes, supporting the use of HAI as a correlate of protection for both vaccine types in children.

中文翻译：

---

儿童血凝抑制抗体和灭活疫苗和减毒活疫苗引发的流感保护作用


背景 血凝素 （HA） 抑制抗体有助于对流感感染的免疫防御。然而，关于疫苗引发的 HA 抗体与儿童对不同流感毒株的保护之间的相关性程度的数据不足，尤其是在比较减毒活流感疫苗 （LAIV） 与灭活流感疫苗 （IIV） 时。方法 我们测量了加拿大 Hutterite 菌落中三价 LAIV （3） 与 IIV （3） 的整群随机对照试验中 3-15 岁参与者的疫苗接种后血凝抑制 （HAI） 滴度。我们使用以疫苗类型为协变量的 Cox 比例风险回归模型，评估了 HAI 滴度作为 3 个流感季节中症状性逆转录聚合酶链反应 （RT-PCR） 确认的流感的预测因子。结果 2013-2014 年、2014-2015 年和 2013-2014 年（每个都是各自流感季节的主要流行毒株）接种后针对 A/H1N1 的 HAI 每增加 log2 单位，确诊流感的风险降低等于 29.6%（95% 置信区间 [CI]，17.1%-39.5%），34.8%（95% CI， 分别为 17.2%–47.9%） 和 31.8% （95% CI，23.8%–38.5%）。在 2012-2013 年，B/Yamagata 特异性 HAI 滴度未观察到流感风险降低，其中以 Yamagata 和 Victoria 菌株的混合物为主。尽管 LAIV3 组的 HAI 滴度总体较低，但 H1N1 和 H3N2 HAI 滴度都与对亚型匹配的流感的保护有关。 结论 LAIV3 和 IIV3 引发的 HA 抗体在疫苗株与流行的流感毒株亚型相匹配的季节与流感感染保护相关，支持使用 HAI 作为儿童两种疫苗类型的保护相关性。