Gu et al. [109] demonstrated that opportunistic pathogens, i.e., Streptococcus, Rothia, Veillonella, Erysipelatoclostridium and Actinomyces, were relatively enriched in stool samples collected from 30 COVID-19 patients; this altered gut microbiota had a positive correlation with the inflammatory marker C-reactive protein (CRP). The gene discussed is CRP; the disease is COVID-19.