# Clinical Characteristics and Cytokines of Children With Lower Respiratory Tract Infection Caused by Influenza A After COVID‐19

## TL;DR

This study examines how prior COVID-19 infection affects the severity of influenza A in children and identifies IP-10 and WBC as key biomarkers for severe cases.

## Contribution

The study identifies IP-10 and WBC as novel diagnostic biomarkers for severe influenza A following prior SARS-CoV-2 infection in children.

## Key findings

- Children with prior SARS-CoV-2 infection had a higher proportion of severe influenza A cases.
- IP-10 and WBC were identified as independent risk factors for severe influenza A following prior SARS-CoV-2 infection.
- Combining IP-10 and WBC improved diagnostic accuracy for disease severity.

## Abstract

To date, there is a lack of research on the clinical characteristics and cytokine profiles in children with influenza A following COVID‐19 infection.

Children with influenza A lower respiratory tract infection who were hospitalized in the Department of Pediatrics of the Affiliated Hospital of Southwest Medical University from March 15 to April 15, 2023, were divided into mild and severe groups according to their symptoms, followed up on the COVID‐19 infection status by telephone, and selected those who had been infected with COVID‐19 for comparison of clinical characteristics and cytokines.

An analysis of influenza A case in children with prior SARS‐CoV‐2 infection revealed that the proportion of previous infection was significantly higher in the severe group compared to the mild group. Univariate analysis indicated significant differences between the two groups in the incidence of convulsions, concurrent or secondary bacterial infections, white blood cell (WBC) count, lymphocyte percentage (L%), neutrophil percentage (N%), and interferon‐induced protein‐10 (IP‐10) (all P < 0.05). Binary logistic regression and receiver operating characteristic (ROC) curve analysis identified IP‐10 and WBC as independent risk factors for severe influenza A following SARS‐CoV‐2 infection, the combination of IP‐10 and WBC demonstrated high diagnostic accuracy for disease severity.

IP‐10 and WBC count serve as diagnostic biomarkers for severe influenza infection following SARS‐CoV‐2 infection, and their combination significantly enhances diagnostic performance.