Supplementary Figure 1. Venn diagram
The Venn diagram shows the interactions between different gut microbiota and the severity of COVID-19. The circles represent mild COVID-19 (blue circle), moderate COVID-19 (yellow circle) and severe COVID-19 (red circle). The numbers in the circles represent the types of gut microbiota. The overlapping areas between the circles represent the number of studies in which the same type of gut microbiota was simultaneously involved in different degrees of COVID-19 infection.