National Public Health Organization, Athens, Greece; European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.
National Public Health Organization, Athens, Greece.
Vaccine. 2020 Mar 10;38(12):2715-2724. doi: 10.1016/j.vaccine.2020.01.083. Epub 2020 Feb 6.
Monitoring seasonal influenza Vaccine Effectiveness (VE) is key to inform vaccination strategies and sustain uptake. Pooling data across multiple seasons increases precision and allows for subgroup analyses, providing more conclusive evidence. Our aim was to assess VE against hospitalization with laboratory-confirmed influenza in Greece over six seasons, from 2013 to 2014 to 2018-2019, using routinely collected surveillance data.
Swab samples from hospitalized patients across the country were tested for influenza by RT-PCR. We used the test-negative design, with patients testing positive for influenza serving as cases and those testing negative serving as controls. VE was calculated as one minus the Odds Ratio (OR) for influenza vaccination, estimated by mixed-effects logistic regression and adjusted for age, sex, hospitalization type (being in intensive care or not), time from symptom onset to swabbing, and calendar time. Stratified estimates by age and hospitalization type were obtained, and also subgroup estimates by influenza type/subtype and season. Antigenic and genetic characterization of a subset of circulating influenza strains was performed.
A total of 3,882 test-positive cases and 5,895 test-negative controls were analyzed. Across all seasons, adjusted VE was 45.5% (95% CI: 31.6-56.6) against all influenza, 62.8% against A(H1N1)pdm09 (95% CI: 40.7-76.7), 28.2% against A(H3N2) (95% CI: 12.0-41.3) and 45.5% against influenza B (95% CI: 29.1-58.1). VE was slightly lower for patients aged 60 years and over, and similar between patients hospitalized inside or outside intensive care. Circulating A(H1N1)pdm09 and B strains were antigenically similar to the vaccine strains, whereas A(H3N2) were not.
Our results confirm the public health benefits from seasonal influenza vaccination, despite the suboptimal effectiveness against A(H3N2) strains. Continued monitoring of VE is essential, and routinely collected surveillance data can be valuable in this regard.
监测季节性流感疫苗效力（VE）是为接种策略提供信息和维持接种率的关键。跨多个季节汇总数据可以提高精度，并允许进行亚组分析，从而提供更具结论性的证据。我们的目的是评估 2013 年至 2018-2019 年六个季节期间，希腊因住院的实验室确诊流感的 VE，使用常规收集的监测数据。
对全国各地住院患者的拭子样本进行流感 RT-PCR 检测。我们使用了阴性检测设计，将流感检测阳性的患者作为病例，流感检测阴性的患者作为对照。VE 是通过混合效应逻辑回归计算得出的，估计值为接种疫苗的优势比（OR），并根据年龄、性别、住院类型（是否在重症监护室）、症状出现到拭子采集的时间以及日历时间进行调整。获得了按年龄和住院类型分层的估计值，并按流感类型/亚型和季节进行了亚组估计值。对一部分循环流感株进行了抗原和遗传特征分析。
共分析了 3882 例阳性病例和 5895 例阴性对照。在所有季节中，调整后的 VE 为所有流感的 45.5%（95%CI：31.6-56.6）、A(H1N1)pdm09 的 62.8%（95%CI：40.7-76.7）、A(H3N2) 的 28.2%（95%CI：12.0-41.3）和 B 型流感的 45.5%（95%CI：29.1-58.1）。60 岁及以上患者的 VE 略低，而在重症监护室内外住院的患者之间相似。循环 A(H1N1)pdm09 和 B 株与疫苗株的抗原相似，而 A(H3N2) 株则不同。
尽管 A(H3N2) 株的效果不理想，但我们的结果证实了季节性流感疫苗接种带来的公共卫生效益。持续监测 VE 至关重要，常规收集的监测数据在这方面具有重要价值。
