biostudies-literatureUnknown15von Ameln Lovison OIt is argued that commensal bacteria in the upper respiratory tract (URT) protect against pathogen colonization and infection, including respiratory viruses. Given that the microbiome can mediate immune modulation, a link between the URT microbiome (URTM) and COVID-19 susceptibility and severity is expected. This 16S metagenomics cross-sectional study assessed URTM composition, metabolic prediction, and association with laboratory biomarkers in non-COVID-19 pneumonia (NO-CoV), moderate (M-CoV), severe (S-CoV) COVID-19 patients, as well as COVID-19-negative, asymptomatic (NC) patients. The S-CoV group exhibited reduced URTM diversity, primarily due to a decreased abundance of eubiotic taxa. Some of these taxa (e.g., <i>Haemophilus</i> sp., <i>Neisseria</i> sp.) were also associated with infFrontiers in cellular and infection microbiology1531084https://www.ebi.ac.uk/biostudies/studies/S-EPMC12106449biostudies-literatureUnveiling the role of the upper respiratory tract microbiome in susceptibility and severity to COVID-19.PMC12106449Weber LGBarth ALMartins AFSimon Coitinho Avon Ameln Lovison OZempulski Volpato FCfalseUnveiling the role of the upper respiratory tract microbiome in susceptibility and severity to COVID-19.It is argued that commensal bacteria in the upper respiratory tract (URT) protect against pathogen colonization and infection, including respiratory viruses. Given that the microbiome can mediate immune modulation, a link between the URT microbiome (URTM) and COVID-19 susceptibility and severity is expected. This 16S metagenomics cross-sectional study assessed URTM composition, metabolic prediction, and association with laboratory biomarkers in non-COVID-19 pneumonia (NO-CoV), moderate (M-CoV), severe (S-CoV) COVID-19 patients, as well as COVID-19-negative, asymptomatic (NC) patients. The S-CoV group exhibited reduced URTM diversity, primarily due to a decreased abundance of eubiotic taxa. Some of these taxa (e.g., <i>Haemophilus</i> sp., <i>Neisseria</i> sp.) were also associated with inf2025-01-01T00:00:00Z20252026-05-29T17:04:09.725Z2026-04-08T05:28:09.445ZS-EPMC121064494043366810.3389/fcimb.2025.1531084