# Gut Microbiota Predicts the Risk of Future COVID-19 Hospitalization and Mortality: Insights From the Population-Based HELIUS Study

## TL;DR

This study shows that gut bacteria, especially those producing butyrate, can predict the risk of severe COVID-19 outcomes like hospitalization or death.

## Contribution

The study demonstrates that gut microbiota composition before infection can influence future severe COVID-19 risk.

## Key findings

- Baseline gut microbiota composition is associated with future severe COVID-19 risk.
- Higher levels of butyrate-producing bacteria are linked to lower risk of severe outcomes.
- Microbiota alterations precede severe disease and may serve as a prevention target.

## Abstract

Gut microbiota are disrupted in patients hospitalized for COVID-19, with a loss of anaerobic bacteria-producing butyrate. Yet, these disruptions could either be a consequence of the infection itself or increase susceptibility from the outset. Here, we investigated whether gut microbiota influence the risk of future COVID-19 hospitalization and mortality. In 5084 participants of a population-based cohort, gut microbiota composition was associated with the risk of future severe COVID-19. Specifically, increased abundances of butyrate-producing bacteria were associated with a lower risk of severe COVID-19. Together, gut microbiota alterations precede severe COVID-19 and may represent a novel target for prevention.

In this large population-based cohort, we found that baseline gut microbiota, especially low levels of butyrate producers, are coupled with a higher risk of hospitalization or mortality due to COVID-19 during follow-up, even after adjustment for potential confounders.