Causal Relationship Between Gut Microbiota and COVID-2019: A Mendelian Randomization Study

Background: There is an enormous risk to public health worldwide from the Coronavirus disease 2019 (COVID-19), and previous observational studies have reported that gut microbiota is associated with an increased risk of COVID-19. However, whether gut microbiota was causally associated with COVID-19 remains unclear. Methods: : Mendelian randomization (MR) analysis was applied to elucidate the causal relationship between gut microbiota and COVID-19 leveraging a large-scale dataset with gut microbiota (N = 18,340) and COVID-19 Host Genetics Initiative (HGI) GWAS data. Inverse-variance weighted (IVW) was used to estimate causal effects. Sensitivity analyses included leave-one-out analysis and Cochran’s Q test. Results: : Seven kinds of gut microbiota were causally associated with an increased risk of COVID-19, and eleven kinds of gut microbiota were causally associated with a lower risk of COVID-19. In addition, this study also indicated that the diversity of gut microbiota was decreased with the aggravation of COVID-19 (susceptibility, hospitalization, and severity). No heterogeneity or pleiotropy was detected for significant estimates. Conclusion: In this study, we found that eighteen kinds of gut microbiota were causally associated with COVID-19, which provides a theoretical basis for guiding clinical work. More attention should be paid to the monitoring of the gut microbiome to identify more risk predictors and potentially beneficial taxa in the prevention and treatment of COVID-19.