Spotlight influenza: Laboratory-confirmed seasonal influenza in people with acute respiratory illness: a literature review and meta-analysis, WHO European Region, 2004 to 2017

Belazi, Sara; Olsen, Sonja J.; Brown, Caroline; Green, Helen K.; Mook, Piers; Nguyen-Van-Tam, Jonathan; Penttinen, Pasi; Lansbury, Louise

Abstract

BackgroundAcross the World Health Organization European Region, there are few estimates of the proportion of people seeking medical care for influenza-like illness or acute respiratory infections and who have laboratory-confirmed seasonal influenza infection.MethodsWe conducted a meta-analysis of data extracted from studies published between 2004 and 2017 and from sentinel data from the European surveillance system (TESSy) between 2004 and 2018. We pooled within-season estimates by influenza type/subtype, setting (outpatient (OP)/inpatient (IP)) and age group to estimate the proportion of people tested who have laboratory-confirmed and medically-attended seasonal influenza in Europe.ResultsIn the literature review, the pooled proportion for all influenza types was 33% (95% confidence interval (CI): 30-36), higher among OP 36% (95% CI: 33-40) than IP 24% (95% CI: 20-29). Pooled estimates for all influenza types by age group were: 0-17 years, 26% (22-31); 18-64 years, 41% (32-50); ≥ 65 years, 33% (27-40). From TESSy data, 33% (31-34) of OP and 24% (21-27) of IP were positive. The highest proportion of influenza A was in people aged 18-64 years (22%, 16-29). By subtype, A(H1N1)pdm09 was highest in 18-64 year-olds (16%, 11-21%) whereas A(H3N2) was highest in those ≥ 65 years (10%, 2-22). For influenza B, the highest proportion of infections was in those aged 18-64 years (15%, 9-24).ConclusionsLaboratory-confirmed influenza accounted for approximately one third of all acute respiratory infections for which medical care was sought during the influenza season.

• Journal Article Type: Article
• Acceptance Date: Dec 8, 2020
• Online Publication Date: Sep 30, 2021
• Publication Date: Sep 30, 2021
• Deposit Date: Dec 15, 2020
• Publicly Available Date: Sep 30, 2021
• Journal: Eurosurveillance
• Print ISSN: 1560-7917
• Electronic ISSN: 1025-496X
• Publisher: European Centre for Disease Control and Prevention (ECDC)
• Peer Reviewed: Peer Reviewed
• Volume: 26
• Issue: 39
• DOI: https://doi.org/10.2807/1560-7917.es.2021.26.39.2000343
• Keywords: Virology; Public Health, Environmental and Occupational Health; Epidemiology
• Public URL: https://nottingham-repository.worktribe.com/output/5149096
• Publisher URL: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2021.26.39.2000343