COVID-19: are digestive disorders linked to the gut microbiota?

Fever, cough and respiratory distress are three symptoms of COVID-19, but they are not the only ones. A first study¹ has reported that half of patients testing positive for coronavirus also complain of digestive symptoms such as loss of appetite, diarrhea and, to a lesser extent, vomiting or abdominal pain.

Digestive symptoms

Excluding loss of appetite, which is not specific to intestinal disorders, about one in five patients involved this study had strictly digestive symptoms which worsened with the aggravation of COVID 19¹. The incidence of diarrhea varied widely between studies (2%-34%)^1,2 but the genetic material of the virus –or even active virus (i.e. able to spread)– was found in patients’ feces^3,4, suggesting that it may multiply in our digestive system. Another study showed an imbalance of the intestinal flora (dysbiosis) in two patients aged 65 and 78 years who subsequently died from COVID 19⁵; however, the link between intestinal dysbiosis and COVID-19 seems of little relevance here since it is well known that elderly people typically display gut flora imbalances⁶. Lastly, a debate⁷ has recently kicked off about the potential role played by Prevotella bacteria in the infection, but to date no scientific evidence has confirmed any such role.

At-risk patients

Admittedly, these initial findings are open to criticism, since the studies were carried out in a limited number of patients⁶, and some of them were not subject to peer review prior to publication⁶. Despite this, the findings warrant caution. For example, on March 16, 2020, the ANSM (French Agency for the Safety of Medecines and Health Products) enhanced precautionary measures in the case of fecal microbiota transplants in order to prevent intestinal infections due to the transmission of other pathogens through Clostridium difficile treatment. Enhanced precautions will also apply to patients suffering from inflammatory bowel disease, particularly to those treated with immunosuppressants, who are more susceptible to viral infections, even if specific data² are still lacking. While they are not advised to discontinue immunosuppressive treatment (the risk of flare-up far exceeds other), they must carefully comply with prevention measures²