Oral and sputum microbiota associated with long COVID severity after hospitalisation

Researchers in the UK Post-hospitalisation COVID-19 study (PHOSP-COVID) examined whether oral and sputum microbiota differed by long COVID severity and symptom phenotype. The prospective multicentre cohort included 771 adults whose microbiota were assessed using 16S ribosomal RNA gene amplicon sequencing at six months after discharge. Participants were grouped by previously defined clusters of ongoing health impairment and symptom subgroups; researchers also assessed associations between keystone microbial taxa and plasma inflammatory proteins.

Among 722 participants with oral rinses and severity-cluster assignments, mean age was 57.5 years and 278 (38.5%) were women. The “very severe” cluster, characterised predominantly by pulmonary disease, was associated with a distinct microbiota profile. Reduced lung function and persistent neurocognitive symptoms were associated with distinct oral profiles, whereas gastrointestinal symptoms were associated with a distinct sputum profile. Keystone taxa shifted towards a higher prevalence of lactic acid bacteria associated with worse health outcomes. Their abundance also correlated with elevated blood inflammatory proteins.

These findings identify microbiota associations with long COVID phenotypes but do not establish that microbial changes cause persistent symptoms or inflammation. The supplied abstract reports no association effect sizes and does not establish clinical utility for microbiota testing or targeted treatment. Applicability beyond previously hospitalised patients remains uncertain; full text was unavailable for assessment.