Hospitalized children with influenza A before, during and after COVID-19 pandemic: a retrospective cohort study

Since the outbreak of COVID-19 in late 2019, the transmission dynamics and clinical presentation patterns of influenza A (Flu A) virus have undergone changes. This article conducted a comparative analysis in clinical characteristics and laboratory results of pediatric patients with Flu A before, during, and after the COVID-19 pandemic. The medical records of 885 children hospitalized with Flu A virus infection at a tertiary hospital in Guangdong Province, China, were retrospectively analyzed. Flu A was confirmed in these cases using a direct immunofluorescence antigen assay. The clinical data for this study span from January 1, 2018, to May 31, 2023. In our study, we observed a total of 340 cases before the COVID-19 pandemic, 196 cases during the pandemic, and 349 cases after the pandemic. Patients after the pandemic had a higher median age on admission (5.66 years, range 3.41-7.70) and exhibited more respiratory symptoms such as cough, sore throat, and nasal stuffiness. The length of hospital stay was longer, and there was a higher percentage of patients with fever duration ≥ 5 days among Flu A patients during the pandemic. Compared to before and during the COVID-19 pandemic, Flu A patients after the pandemic showed significantly reduced white blood cell (WBC) and platelet (PLT) counts (P