Lower gut abundance of Eubacterium rectale is linked to COVID-19 mortality.
Level 4 - case-series / case-control
Ecological cross-sectional correlation study linking aggregate country-level COVID-19 mortality to public gut metagenomic datasets.
PubMed 37743871 · doi:10.3389/fcimb.2023.1249069
What was done
Gut metagenomic data from 2,871 adult subjects across 16 countries were retrieved from ExperimentHub, and COVID-19 mortality data between January 22, 2020, and December 8, 2020, were obtained from the Johns Hopkins Coronavirus Resource Center. An adjusted stable mortality rate (SMR) was calculated for each country and correlated with the mean relative abundance of healthy adult gut bacterial species (excluding species with prevalence <0.2).
What was found
Microbiome β-diversity was significantly higher in countries with high SMR compared to those with median or low SMR (p < 0.001). The mean relative abundances of two butyrate producers, Eubacterium rectale and Roseburia intestinalis, were negatively correlated with SMR, with reductions linked to more severe COVID-19 manifestation. Exact correlation coefficients, effect sizes, and confidence intervals were not reported in the abstract.
Why it matters
This study generates an ecological, population-level hypothesis linking lower baseline abundances of specific butyrate-producing gut bacteria to higher national COVID-19 mortality rates.
Limits
This is an ecological study correlating country-level mortality statistics with separate healthy adult metagenomic datasets, carrying a high risk of ecological fallacy. It lacks individual-level infection, microbiome, and clinical outcome data, and the abstract does not report numerical correlation values or adjustments for major population confounders such as age, healthcare capacity, or public health policies.
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