According to WHO, about 6% of people worldwide who get COVID-19, roughly 400 million people, later develop a long-lasting form of the illness. That shows the condition remains a significant public health challenge.
In 2021, during the COVID-19 pandemic, the University of Louvain (UCLouvain, Belgium) and its hospital, the Cliniques universitaires Saint-Luc, launched a large-scale study to see whether long-term symptoms could be predicted during the acute phase of infection. The goal was to better understand the biological mechanisms involved and potentially identify a preventive treatment.
A Bacterium Linked to Recovery
After five years of research, scientists identified an important role for Dolosigranulum pigrum, a bacterium that naturally lives in the respiratory microbiome. Higher levels of this bacterium were associated with a lower likelihood that long Covid symptoms would persist.
Jean Cyr Yombi, Leïla Belkir, and Julien De Greef, UCLouvain professors and infectious disease specialists at the Cliniques universitaires Saint-Luc, examined the severity of long Covid symptoms in 156 patients. They focused mainly on severe fatigue, cognitive problems, and respiratory issues (shortness of breath).
Laure Elens and Patrice Cani, also UCLouvain professors, along with Bradley Ward, a postdoctoral researcher at the UCLouvain Louvain Drug Research Institute, then analyzed blood samples and nasopharyngeal swabs for molecular signatures linked to this more severe form of the disease. These signatures may help explain why symptoms persist in some patients but not in others.
Clues From the Respiratory Microbiome
UCLouvain and Cliniques universitaires Saint-Luc researchers stated, “This study suggests that certain so-called protective bacteria in the respiratory microbiome may be associated with improved recovery following viral respiratory infections (such as long Covid ), and that their alteration (particularly in the context of severe infection or non-targeted antibiotic therapy) may influence longer-term clinical outcomes.”
