{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T21:36:25Z","timestamp":1768858585755,"version":"3.49.0"},"reference-count":29,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,1,17]],"date-time":"2026-01-17T00:00:00Z","timestamp":1768608000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Background: The COVID-19 pandemic substantially altered the epidemiology of respiratory infections. Its impact on the clinical course of influenza in hospitalised children remains insufficiently characterised. Objectives: We aimed to compare the clinical course, complications, and selected laboratory parameters of influenza in children before, during, and after the COVID-19 pandemic. Methods: This single-centre retrospective study included 553 children hospitalised with laboratory-confirmed influenza between September 2017 and August 2025. Patients were divided into three groups: pre-pandemic, pandemic, and post-pandemic. Clinical complications and inflammatory markers (CRP, PCT, neutrophil counts) were analysed. Results: Influenza-related complications occurred in 59.5% of patients and were significantly more frequent after the pandemic compared to the pre-pandemic period (64.3% vs. 52.9%, p = 0.02). Pneumonia was the most common complication across all groups, but its incidence was lowest during the pandemic. Myositis occurred most frequently during the pandemic and appears to coincide with a higher proportion of influenza B infections. No significant differences were observed in CRP, PCT concentrations, or neutropenia rates between groups. Conclusions: The COVID-19 pandemic influenced the clinical presentation of influenza in children, with a post-pandemic increase in complications. These findings may reflect delayed access to healthcare and the phenomenon of immunity debt, highlighting the need for continued surveillance and preventive strategies.<\/jats:p>","DOI":"10.3390\/life16010154","type":"journal-article","created":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T08:23:56Z","timestamp":1768811036000},"page":"154","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Impact of the COVID-19 Pandemic on the Clinical Course of Influenza in Hospitalised Children in the Years 2017\u20132025"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7300-4051","authenticated-orcid":false,"given":"Zuzanna","family":"Wasielewska","sequence":"first","affiliation":[{"name":"Department of Infectious Diseases and Hepatology, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, 87-100 Toru\u0144, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-5144-9513","authenticated-orcid":false,"given":"Justyna","family":"Franczak","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases and Hepatology, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, 87-100 Toru\u0144, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Krystyna","family":"Dobrowolska","sequence":"additional","affiliation":[{"name":"Collegium Medicum, Jan Kochanowski University, 25-369 Kielce, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6299-2103","authenticated-orcid":false,"given":"Justyna","family":"Moppert","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases and Hepatology, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, 87-100 Toru\u0144, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ma\u0142gorzata","family":"Sobolewska-Pilarczyk","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases and Hepatology, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, 87-100 Toru\u0144, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6044-0425","authenticated-orcid":false,"given":"Ma\u0142gorzata","family":"Paw\u0142owska","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases and Hepatology, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, 87-100 Toru\u0144, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,17]]},"reference":[{"key":"ref_1","unstructured":"(2025, December 15). 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