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 < 0.001), along with elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in laboratory indexes (P < 0.001). Furthermore, more hospitalized children after the pandemic were diagnosed with benign acute childhood myositis (BACM).

Our research results indicates a significant decrease in Flu A cases during the COVID-19 pandemic, and hospitalized children with Flu A have more severe clinical symptoms after the COVID-19 pandemic. These findings have implications for public health policy and clinical management of Flu A cases.

Not applicable.