Background The 2023-2024 influenza season had predominant influenza A(H1N1)pdm09 virus activity, but A(H3N2) and B viruses co-circulated. Seasonal influenza vaccine strains were well-matched to these viruses. Methods Using health care encounters data from health systems in 8 states, we evaluated influenza vaccine effectiveness (VE) against influenza-associated medical encounters from October 2023-April 2024. Using a test-negative design, we compared the odds of vaccination between patients with an acute respiratory illness (ARI) who tested positive (cases) versus negative (controls) for influenza by molecular assay, adjusting for confounders. VE was stratified by age group, influenza type (overall, influenza A, influenza B), and care setting (hospitalization, emergency department or urgent care [ED/UC] encounter). Results Overall, 74,000 encounters in children and adolescents aged 6 months – 17 years (3,479 hospitalizations, 70,521 ED/UC encounters) and 267,606 in adults aged ≥18 years (66,828 hospitalizations, 200,778 ED/UC encounters) were included. Across care settings, among children and adolescents 15% (2,758/17,833) of cases versus 32% (18,240/56,167) of controls had received vaccination. Among adults, 25% (11,632/46,614) of cases versus 44% (97,811/220,992) of controls across care settings had received vaccination. VE was 58% (95% confidence interval [95% CI]: 44-69%) against hospitalization and 58% (95% CI: 56-60%) against ED/UC encounters for children and adolescents, and 39% (95% CI: 35-43) against hospitalization and 47% (95% CI: 46-49%) against ED/UC encounters for adults. Across age groups, VE was higher against influenza B than influenza A. Conclusions Influenza vaccines provided protection against influenza-associated illness across health care settings and age groups during the 2023-2024 influenza season.

中文翻译：

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2023-2024 年流感季节流感疫苗对儿童、青少年和成人住院和急诊科或紧急护理的有效性，美国


背景 2023-2024 年流感季节以甲型流感 （H1N1） pdm09 病毒为主，但甲型 （H3N2） 和乙型流感病毒同时传播。季节性流感疫苗株与这些病毒匹配良好。方法使用来自 8 个州卫生系统的医疗保健遭遇数据，我们评估了 2023 年 10 月至 2024 年 4 月流感疫苗对流感相关医疗遭遇的有效性 （VE）。使用检测阴性设计，我们通过分子检测比较了流感检测阳性（病例）的急性呼吸系统疾病 （ARI） 患者与流感检测阴性（对照）患者的疫苗接种几率，并调整了混杂因素。VE 按年龄组、流感类型 （总体上是甲型流感、乙型流感） 和护理环境 （住院、急诊科或紧急护理 [ED/UC] 遭遇） 分层。结果总体而言，包括 74,000 例 6 个月至 17 岁的儿童和青少年（3,479 例住院，70,521 例 ED/UC 就诊）和 267,606 例 ≥18 岁成人（66,828 例住院，200,778 例 ED/UC 就诊）。在整个护理机构中，儿童和青少年中 15% （2,758/17,833） 的病例与 32% （18,240/56,167） 的对照组接受了疫苗接种。在成年人中，25% （11,632/46,614） 的病例与 44% （97,811/220,992） 的对照者接受了疫苗接种。儿童和青少年住院治疗的 VE 为 58% （95% 置信区间 [95% CI]： 44-69%），儿童和青少年 ED/UC 就诊的 VE 为 58% （95% CI： 56-60%），住院治疗的 39% （95% CI： 35-43） 和成人的 ED/UC 就诊为 47% （95% CI： 46-49%）。在所有年龄组中，乙型流感的 VE 高于甲型流感。 结论 在 2023-2024 年流感季节，流感疫苗为医疗保健机构和年龄组提供了对流感相关疾病的保护。