Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee, USA.
Clin Infect Dis. 2021 Aug 16;73(4):e947-e954. doi: 10.1093/cid/ciab060.
The 2019-2020 influenza season was characterized by early onset with B/Victoria followed by A(H1N1)pdm09 viruses. Emergence of new B/Victoria viruses raised concerns about possible vaccine mismatch. We estimated vaccine effectiveness (VE) against influenza-associated hospitalizations and emergency department (ED) visits among children in the United States.
We assessed VE among children aged 6 months-17 years with acute respiratory illness and ≤10 days of symptoms enrolled at 7 pediatric medical centers in the New Vaccine Surveillance Network. Combined midturbinate/throat swabs were tested for influenza virus using molecular assays. Vaccination history was collected from parental report, state immunization information systems, and/or provider records. We estimated VE from a test-negative design using logistic regression to compare odds of vaccination among children testing positive vs negative for influenza.
Among 2029 inpatients, 335 (17%) were influenza positive: 37% with influenza B/Victoria alone and 44% with influenza A(H1N1)pdm09 alone. VE was 62% (95% confidence interval [CI], 52%-71%) for influenza-related hospitalizations, 54% (95% CI, 33%-69%) for B/Victoria viruses, and 64% (95% CI, 49%-75%) for A(H1N1)pdm09. Among 2102 ED patients, 671 (32%) were influenza positive: 47% with influenza B/Victoria alone and 42% with influenza A(H1N1)pdm09 alone. VE was 56% (95% CI, 46%-65%) for an influenza-related ED visit, 55% (95% CI, 40%-66%) for B/Victoria viruses, and 53% (95% CI, 37%-65%) for A(H1N1)pdm09.
Influenza vaccination provided significant protection against laboratory-confirmed influenza-associated hospitalizations and ED visits associated with the 2 predominantly circulating influenza viruses among children, including against the emerging B/Victoria virus subclade.
2019-2020 年流感季节的特点是 B/Victoria 亚型的病毒提前出现，随后是 A(H1N1)pdm09 病毒。新型 B/Victoria 病毒的出现引起了人们对可能出现疫苗不匹配的担忧。我们评估了美国儿童因流感相关住院和急诊（ED）就诊的疫苗有效性（VE）。
我们评估了 7 家儿科医疗中心的新疫苗监测网络中，急性呼吸道疾病且症状持续时间≤10 天的 6 个月至 17 岁儿童的 VE。使用分子检测方法对中鼻甲/咽喉合并拭子进行流感病毒检测。通过父母报告、州免疫信息系统和/或提供者记录收集疫苗接种史。我们使用逻辑回归从测试阴性设计中估计 VE，以比较流感检测阳性与阴性儿童的疫苗接种几率。
在 2029 名住院患者中，335 例（17%）为流感阳性：37%为单独的 B/Victoria 型，44%为单独的 A(H1N1)pdm09 型。流感相关住院治疗的 VE 为 62%（95%置信区间[CI]，52%-71%），B/Victoria 病毒为 54%（95% CI，33%-69%），A(H1N1)pdm09 为 64%（95% CI，49%-75%）。在 2102 名 ED 患者中，671 例（32%）为流感阳性：47%为单独的 B/Victoria 型，42%为单独的 A(H1N1)pdm09 型。与流感相关的 ED 就诊的 VE 为 56%（95% CI，46%-65%），B/Victoria 病毒为 55%（95% CI，40%-66%），A(H1N1)pdm09 为 53%（95% CI，37%-65%）。
流感疫苗对实验室确诊的儿童流感相关住院和 ED 就诊提供了显著保护，包括对新兴的 B/Victoria 病毒亚系的保护。
