# Local and systemic host responses to influenza and concurrent or sequential SARS-CoV-2 infection

## TL;DR

This paper reviews how coinfection with influenza and SARS-CoV-2 worsens lung damage and inflammation, offering insights for better treatment.

## Contribution

The paper provides a novel synthesis of mechanisms behind worsened outcomes in dual viral infections.

## Key findings

- Coinfection with influenza and SARS-CoV-2 increases pulmonary pathology.
- Systemic inflammation is heightened in individuals with dual infections.
- Understanding these mechanisms may improve prevention and treatment strategies.

## Abstract

Influenza is an acute respiratory infectious disease caused by the influenza virus, which has been circulating in humans for over a century. In contrast, COVID-19, caused by the novel SARS-CoV-2, emerged recently in December 2019. Following nearly four years of pandemic, the acute phase of SARS-CoV-2 has transitioned towards an endemic state, suggesting a trend of long-term coexistence with humans. Concurrent or sequential coinfection with influenza and SARS-CoV-2 has been clinically observed to exacerbate pulmonary pathology and systemic inflammation in affected individuals. This review discusses the impact and elucidates the potential underlying mechanisms by which influenza and SARS-CoV-2 coinfection aggravates local lung injury and systemic host responses, aiming to inform improved prevention and clinical management strategies.