Scientists have linked severe long-term COVID-19 to changes in the lung microbiome

In people with the most severe manifestations of long-term COVID-19, scientists have found differences in the composition of microorganisms living in the oral cavity and respiratory tract. These features have also been linked to impaired lung function, cognitive difficulties, and digestive problems. The role of the microbiome can play in the consequences of coronavirus infection is described in the Izvestia article.

Microbiome in severe long-term COVID-19

According to a study published in the European Respiratory Journal (ERJ), scientists have found a link between the severity of long-term COVID-19 and the composition of the oral and respiratory microbiome.

The study included 771 people who were treated for COVID-19 in 38 UK hospitals from February 2020 to March 2021. Five months after discharge, the patients were divided into four groups, depending on the severity of the remaining symptoms: from mild manifestations and good recovery to severe physical, mental and cognitive impairments.

What changes have the scientists found?

Six months after discharge, the researchers collected saliva and sputum samples from the participants. Using DNA sequencing, they determined which microorganisms were present in the samples, assessed their diversity and quantity, and then compared the results with the patients' symptoms.

In people with the most severe manifestations of long-term COVID-19, the composition of the oral cavity and respiratory tract microbiome was markedly different from that of patients without severe symptoms. Certain features of the microbiome have been associated with decreased lung function, cognitive impairments, including difficulties with memory, attention, and concentration, as well as gastrointestinal symptoms such as pain, nausea, diarrhea, and loss of appetite.

The researchers also identified an increased number of lactic acid-producing bacteria. Their presence was associated with signs of inflammation in the blood samples. At the same time, the results show the relationship between the features of the microbiome and the symptoms, but do not prove that it is the microorganisms that cause these disorders.

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Why do scientists study respiratory tract microorganisms?

Previously, scientists had already detected changes in the intestinal microbiome in people with this condition, and in the new work, attention was focused on the oral cavity and respiratory tract.

According to the scientist, it is not yet known whether the identified features of the microbiome existed before coronavirus infection or appeared after infection. The researchers will also have to figure out how the composition of microorganisms changes in subsequent years and whether it recovers over time.

Will the discovery help to find new ways of treatment

The authors of the study believe that the data obtained can become the basis for further study of the mechanisms of long-term COVID-19. If the relationship between the features of the microbiome and the severity of symptoms is confirmed, this may help in developing ways to predict, prevent, and treat the most severe forms of the condition.

However, the results cannot yet be directly used to select a treatment. Researchers need to establish what role changes in the microbiome play in the development of symptoms and whether they can be safely treated to improve the condition of patients.