TABLE 2.

Microbial markers as a diagnostic model for COVID-19.

Study cohort	Characterized microbiota	Diagnostic efficacy	Ref.
Gut microbiota 30 COVID-19 patients, 24influenza A (H1N1) patients, 30 matched healthy controls (HC)	Fusicatenibacter, Romboutsia, Intestinibacter, Actinomyces, Erysipelatoclostridium	89% (95% CI, 80%–97%)	Gu et al., 2020
Gut microbiota Discovery cohort (37 confirmed patients, 10 healthy controls)	Eubacterium hallii, Coprococcus catus, Bacteroides vulgatus, Prevotella bivia etc., a total of 15 species	93.3% (95% CI of 79.8–100.0%, p < 0.001) in cross-regional validation of Changsha:10 COVID-19 patients	Li S. et al., 2021
Gut microbiota Discovery cohort (24 confirmed patients, 48 healthy controls)	OTU1741 (Halomonas), OTU1314 (Pelagibacterium), OTU1473 (Faecalibacterium), OTU1000 (Blautia), etc., a total of 7 OTUs	99.31% (95% CI 97.66%-100%, p < 0.0001) in validation cohort:12 confirmed patients, 24 healthy controls	Ren et al., 2021
Oropharyngeal microbiota Discovery cohort (48 confirmed patients, 94 healthy controls)	OTU10 (Alloprevotella), OTU26 (Prevotella), OTU34 (Halomonas), OTU5 (Haemophilus), etc., a total of 8 OTUs	99.3% (95% CI 98.21%-100%, p < 0.0001) in validation cohort:25 confirmed patients, 46 healthy controls	Gao et al., 2021
Oral microbiota Discovery cohort of Henan (48 confirmed patients, 100 healthy controls)	OTU1642 (Haemophilus), OTU1277 (Actinomyces), OTU1868 (Prevotella), OTU648 (Oribacterium), OTU1454 (Fusobacterium), etc., a total of 8 OTUs	95.75% (95% CI 90.99%-100%, p < 0.0001) in validation cohort: 24 confirmed patients, 50 healthy controls p < 87.24% (95% CI 80.5% to 93.98%, p < 0.0001) in cross-regional validation of Hangzhou:74 confirmed patients	Ren et al., 2021