# Age-related immune response disparities between adults and children with severe COVID-19: a case–control study in China

## TL;DR

This study compares immune responses in adults and children with severe COVID-19 in China, finding significant differences that could inform treatment approaches.

## Contribution

The study identifies age-related disparities in immune responses and cytokine profiles in severe COVID-19 patients using a case–control design with propensity score matching.

## Key findings

- Adults with severe COVID-19 showed lymphocyte exhaustion, elevated NEU/LYM ratio, and cytokine storm markers like IL-6 and TNF-α.
- Children exhibited distinct systemic immune responses compared to adults, suggesting different disease mechanisms.
- Propensity score matching helped mitigate confounding factors, revealing clear immune response disparities between age groups.

## Abstract

Elucidation of immune response differences is critical for uncovering underlying mechanisms and developing potential intervention measures among adults and children with COVID-19.

In this retrospective study, we analyzed serum biochemical markers and cytokine profiles among adults and children with COVID-19 in the First People’s Hospital of Chenzhou in Hunan, China from 1 December 2022 to 13 February 2023. A case–control study was conducted using propensity score matching (PSM) to mitigate possible confounding factors.

The significant differences observed included lymphocyte exhaustion, an increased neutrophil-to-lymphocyte (NEU/LYM) ratio, high levels of C-reactive protein (CRP), and a cytokine storm, characterized by high levels of Th1 proinflammatory cytokines, including interleukin 1β (IL-1β), IL-6, IL-8, interferon type I (IFN-γ), and tumor necrosis factor (TNF-α) in the lung among severe adult COVID-19 patients. Additionally, systemic immune responses were observed in children with COVID-19.

Significant differences in immune responses between adults and children with COVID-19 highlight the different mechanisms and potential intervention measures of COVID-19.