Long COVID severity tied to distinct oral and lung bacterial profiles
A study of 771 people treated for COVID-19 found that those with long COVID had different bacterial communities in their mouths and lungs. Lung microbiome differences were associated with respiratory symptoms as well as cognitive and digestive problems. Researchers suggest these findings may help explain why some people develop long COVID and could point toward new treatments.
The PHOSP-COVID project tracked 771 patients treated for COVID-19 at 38 U.K. hospitals from February 2020 to March 2021. Five months after discharge, they were placed into four groups according to long-COVID severity, ranging from mild recovery to very severe physical, mental, and cognitive impairment.
Six months after discharge, mouth and airway samples were analyzed with genetic sequencing to identify microbes. Very severe cases had distinct bacterial communities. Particular microbial shifts accompanied poorer respiratory function, mental fogginess, memory and concentration trouble, and digestive complaints. Lactic-acid-producing bacteria were more plentiful and associated with blood inflammation markers.
These findings may matter to people living with persistent symptoms after COVID-19, especially those with breathing, cognitive, or digestive difficulties. If oral and lung bacterial patterns help explain long COVID, clinicians could eventually use them to identify higher-risk patients or guide treatments. However, the study links microbial differences to symptoms rather than proving cause, so any societal benefit would depend on further research confirming whether these profiles can be changed to improve recovery.