Fig. 1.

Gut microbial alpha-diversity in three groups of study subjects, based on 16S rRNA sequences in fecal samples. a Species richness and evenness of fecal samples from Controls (n = 20), COVID-19-positive patients (n = 20), and COVID-19-recovered patients (n = 20) were measured in terms of observed OTUs and Pielou evenness, respectively. Differences between groups were not significant using Welch’s t-test. b Species richness in subjects with or without antibiotic use, and in relation to sex, was estimated by observed OTUs. (Table 1 indicates the number of subjects in each group). *p < 0.05 by Welch’s t-test. c, d Alpha-diversity in subjects without (c) or with (d) antibiotic use was compared between groups using the metrics of observed OTUs, Shannon index, and Pielou evenness. *p < 0.05 by Welch’s t-test