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Kislaya I, Torres AR, Gomes L, Melo A, Machado A, Henriques C, Verdasca N, Guiomar R, Rodrigues AP, Surveillance Network NI. End of season 2022/2023 quadrivalent influenza vaccine effectiveness in preventing influenza in primary care in Portugal. Hum Vaccin Immunother 2023; 19:2263219. [PMID: 37964588 PMCID: PMC10653732 DOI: 10.1080/21645515.2023.2263219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 09/21/2023] [Indexed: 11/16/2023] Open
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.
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Affiliation(s)
- Irina Kislaya
- Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Ana Rita Torres
- Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Licínia Gomes
- Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Aryse Melo
- Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Ausenda Machado
- Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Camila Henriques
- Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Nuno Verdasca
- Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Raquel Guiomar
- Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
| | - Ana Paula Rodrigues
- Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge IP (INSA, IP), Lisboa, Portugal
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