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End of season 2022/2023 quadrivalent influenza vaccine effectiveness in preventing influenza in primary care in Portugal.

ABSTRACT: Using a test-negative case-control design, we aim to estimate influenza vaccine effectiveness (VE) against medically attended laboratory-confirmed influenza in Portugal in 2022/2023 season. Between week 41/2022 and week 14/2023, data on 592 patients with influenza-like illness aged 18 or more years old were collected by the national sentinel influenza surveillance system in primary care settings. Of those, 218 were positive for influenza and 374 were negative controls. We estimated seasonal influenza VE as (1-odds ratio)*100% of being vaccinated in laboratory-confirmed influenza cases vs. negative controls using logistic regression model adjusted for age group, sex, presence of chronic conditions, and month of symptoms onset. The seasonal VE was 59.3% (95% confidence interval (CI): 27.3 to 77.3) against any laboratory-confirmed influenza and not statistically significant 44.5% (95% CI: -5.6 to 70.8) against influenza A (H3N2). In the 2022/2023 season, characterized by early and low influenza activity and predominant A (H3N2) circulation, vaccination provided a moderate protection against medically attended laboratory-confirmed influenza in primary care.

SUBMITTER: Kislaya I

PROVIDER: S-EPMC10653732 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

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End of season 2022/2023 quadrivalent influenza vaccine effectiveness in preventing influenza in primary care in Portugal.

Kislaya Irina I Torres Ana Rita AR Gomes Licínia L Melo Aryse A Machado Ausenda A Henriques Camila C Verdasca Nuno N Guiomar Raquel R Rodrigues Ana Paula AP Surveillance Network National Influenza NI

Human vaccines & immunotherapeutics 20231115 3

Using a test-negative case-control design, we aim to estimate influenza vaccine effectiveness (VE) against medically attended laboratory-confirmed influenza in Portugal in 2022/2023 season. Between week 41/2022 and week 14/2023, data on 592 patients with influenza-like illness aged 18 or more years old were collected by the national sentinel influenza surveillance system in primary care settings. Of those, 218 were positive for influenza and 374 were negative controls. We estimated seasonal infl ...[more]

PMID: 37964588

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Project description:BackgroundDuring the 2023-2024 season, the influenza epidemic in South Korea peaked earlier, and the influenza vaccination rate among individuals aged ≥ 65 was high (82.2%). However, data on real-world vaccine effectiveness against influenza are lacking.MethodsFrom November 2023 to April 2024, we conducted a multicenter retrospective case-control study on adult patients aged ≥ 18 years who presented with influenza-like illness at seven medical centers as a part of a hospital-based influenza morbidity and mortality surveillance (HIMM) program in South Korea. Demographic and clinical data were collected from questionnaire surveys and electronic medical records. Using a test-negative design, we assessed the effectiveness of the 2023-2024 seasonal influenza vaccine, with age, sex, and comorbidities included as covariates.ResultsA total of 3390 participants were enrolled through the HIMM system, including 1695 patients with either rapid antigen test (RAT) or real-time reverse-transcription polymerase chain reaction (RT-PCR) positive results and controls matched for age, sex, and months of registration. Among the 1696 influenza-positive patients, 1584 (93.5%) underwent RAT, with 88.9% testing positive for influenza A and 11.1% for influenza B. During the study periods, the overall vaccine effectiveness (VE) was 24.3% (95% confidence interval (CI), 11.5 to 35.2). The VE was insignificant when limited to older adults aged ≥ 65 years (13.5%; 95% CI, -17.9 to 36.6). In the subgroup analysis by subtype, the VE was 19.0% (95% CI, 5.0 to 31.0) for influenza A and 56.3% (95% CI, 35.3 to 70.6) for influenza B. Notably, influenza VE was 20.4% (95% CI, 2.9 to 34.8) in the early period (November to December) but decreased to 12.4% (95% CI, -14.9 to 33.2) in the late period (January to April).ConclusionDuring the 2023-2024 season, the influenza vaccine showed a modest effectiveness (24.3%) against laboratory-confirmed influenza, which was particularly higher for influenza B. Because the VE was insignificant in older adults, particularly during the late period, better immunogenic influenza vaccines with longer-lasting protection should be considered.

Dataset Information

End of season 2022/2023 quadrivalent influenza vaccine effectiveness in preventing influenza in primary care in Portugal.

Publications

End of season 2022/2023 quadrivalent influenza vaccine effectiveness in preventing influenza in primary care in Portugal.

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