Health · Medical Research · 1 hr ago
Severe long Covid linked to differences in mouth and lung microbes
Researchers in the UK studied 771 people who had been treated for Covid-19 in hospital between February 2020 and March 2021.
They grouped participants by the severity of their symptoms five months after leaving hospital.
Six months after discharge, they tested saliva and sputum samples to identify the microbes in participants’ mouths and lungs.
People with very severe long Covid had notably different mixes of microbes from those without severe symptoms.
Some differences were associated with breathing problems, brain fog, memory and concentration difficulties, and digestive symptoms.
The study also found that bacteria that produce lactic acid were more abundant in some people with symptoms and were linked to signs of inflammation in their blood.
The findings may help researchers understand long Covid, whose causes remain unknown, but the study does not show whether the microbial changes cause symptoms or result from them.
A study of 771 people found that very severe long Covid was associated with distinct differences in the bacteria in their mouths and lungs.
The lung microbiome differences were linked to respiratory, cognitive and digestive symptoms.
Researchers also found an association between symptom-related microbiome changes and bacteria that produce lactic acid, as well as signs of inflammation in blood samples.
The findings may help explain long Covid and point to possible ways to treat it, but the study does not establish whether the microbiome changes cause the condition.
- Who
- Researchers studied 771 people who had been treated for Covid-19.
- What
- The study found differences in mouth and lung microbiomes associated with long Covid symptoms.
- When
- The study was published on 12 October 2026. Participants were treated between February 2020 and March 2021.
- Where
- Participants were treated at 38 UK hospitals.
- Why
- Researchers examined whether microbiome changes may help explain long Covid and point to possible treatments.
This story does not have two clearly opposing sides.
The microbiome is important to maintain health throughout the body, so it is a strong candidate for something that may contribute to long Covid.
People who had the worst symptoms five to six months after Covid infection had big changes in the microbiome in their mouth and lungs.
We also found that changes in the airway microbiome were linked not just to lung problems, but also to symptoms like brain fog and gut symptoms, suggesting the lung microbiome could have effects on health more broadly.
Participants were treated for Covid-19 at one of 38 UK hospitals.
Researchers grouped participants by the severity of their symptoms.
Researchers collected saliva and sputum samples for DNA sequencing.
The study was published in the European Respiratory Journal.
- Participants
- 771 people
- Hospitals
- 38 UK hospitals
- Symptom assessment
- Five months after discharge
- Samples collected
- Six months after discharge
- Publication
- European Respiratory Journal, 12 October 2026
Sources
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