Chung Jessie R, Price Ashley M, Zimmerman Richard K, Moehling Geffel Krissy, House Stacey L, Curley Tara, Wernli Karen J, Phillips C Hallie, Martin Emily T, Vaughn Ivana A, Murugan Vel, Scotch Matthew, Saade Elie A, Faryar Kiran A, Gaglani Manjusha, Ramm Jason D, Williams Olivia L, Walter Emmanuel B, Kirby Marie, Keong Lisa M, Kondor Rebecca, Ellington Sascha R, Flannery Brendan
Influenza Division, US Centers for Disease Control and Prevention, Atlanta, GA, USA.
University of Pittsburgh School of Medicine, Department of Family Medicine, Pittsburgh, PA, USA.
Clin Infect Dis. 2025 Jan 6. doi: 10.1093/cid/ciae658.
The 2023-24 U.S. influenza season was characterized by a predominance of A(H1N1)pdm09 virus circulation with co-circulation of A(H3N2) and B/Victoria viruses. We estimated vaccine effectiveness (VE) in the United States against mild-to-moderate medically attended influenza illness in the 2023-24 season.
We enrolled outpatients aged ≥8 months with acute respiratory illness in 7 states. Respiratory specimens were tested for influenza type/subtype by reverse-transcriptase polymerase chain reaction (RT-PCR). Influenza VE was estimated with a test-negative design comparing odds of testing positive for influenza among vaccinated versus unvaccinated participants. We estimated VE by virus sub-type/lineage and A(H1N1)pdm09 genetic subclades.
Among 6,589 enrolled patients, 1,770 (27%) tested positive for influenza including 796 A(H1N1)pdm09, 563 B/Victoria, and 323 A(H3N2). Vaccine effectiveness against any influenza illness was 41% (95% Confidence Interval [CI]: 32 to 49): 28% (95% CI: 13 to 40) against influenza A(H1N1)pdm09, 68% (95% CI: 59 to 76) against B/Victoria, and 30% (95% CI: 9 to 47) against A(H3N2). Statistically significant protection against any influenza was found for all age groups except adults aged 50-64 years. Lack of protection in this age group was specific to influenza A-associated illness. We observed differences in VE by birth cohort and A(H1N1)pdm09 virus genetic subclade.
Vaccination reduced outpatient medically attended influenza overall by 41% and provided protection overall against circulating influenza A and B viruses. Serologic studies would help inform differences observed by age groups.
2023 - 2024年美国流感季的特点是A(H1N1)pdm09病毒占主导地位，同时A(H3N2)和B/维多利亚病毒共同流行。我们评估了美国2023 - 2024年流感疫苗针对轻度至中度需就医的流感疾病的有效性（VE）。
我们在7个州招募了年龄≥8个月的急性呼吸道疾病门诊患者。通过逆转录聚合酶链反应（RT-PCR）对呼吸道标本进行流感型/亚型检测。采用检测阴性设计评估流感疫苗有效性，比较接种疫苗和未接种疫苗参与者中流感检测呈阳性的几率。我们按病毒亚型/谱系以及A(H1N1)pdm09基因亚分支评估疫苗有效性。
在6589名登记患者中，1770人（27%）流感检测呈阳性，其中包括796例A(H1N1)pdm09、563例B/维多利亚和323例A(H3N2)。针对任何流感疾病的疫苗有效性为41%（95%置信区间[CI]：32至49）：针对A(H1N1)pdm09流感为28%（95%CI：13至40），针对B/维多利亚流感为68%（95%CI：59至76），针对A(H3N2)流感为30%（95%CI：9至47）。除50 - 64岁成年人外，所有年龄组针对任何流感均发现有统计学意义的保护作用。该年龄组缺乏保护作用仅针对甲型流感相关疾病。我们观察到按出生队列和A(H1N1)pdm09病毒基因亚分支划分的疫苗有效性存在差异。
接种疫苗使门诊需就医的流感总体减少了41%，并对流行的甲型和乙型流感病毒提供了总体保护。血清学研究将有助于了解各年龄组观察到的差异。
