ABSTRACT
Background: SARS-CoV-2 is a respiratoryvirus, and we would expect the symptoms to bedirectly associated with the respiratory system.Nevertheless, within recent investigations, scientists have observed that most of the patients withCOVID-19 have had gastrointestinal manifestations such as: gastroenteritis, diarrhea, vomit,nausea, and stomachache.Objectives: The main objective is the understanding, through the physiopathology, of SARSCoV-2 and the lung-gut axis, also the relationthat exists between the level of gastrointestinaldysbiosis in patients infected with SARS-CoV-2and the influence of microbiota.Methods: Through the PubMed platform andGoogle Scholar, we found the reviewed articles.The key words used were: gut-lung axis, dysbiosis, ACE2 and RAAS.Results: It's been demonstrated the relationbetween SARS-CoV-2 and dysbiosis of gastrointestinal microbiota, being this the responsible ofthe severity of the COVID-19. Also the ACE2acts as a receptor for de SARS-CoV-2 to decreaseits presence in the gut giving as a result inflammation process, vasoconstriction and fibrosis thanksto the reduction of the protective barrier increasing the ACE levels that change RAAS generatingsymptoms like: gastroenteritis, diarrhea, vomit,nausea, and stomachache. Discussion: The lung-gut axis has a big influence in the severity of the symptoms caused bythe SARS-CoV-2, both the respiratory and gastrointestinal symptoms. This is because this axisacts in a bidirectional way, involving directly thegastrointestinal and the respiratory systems. Thisis the reason we conclude that if a patient has ahealthy microbiota, the disease is more likely tobe light or medium light, but if the patient doesn'thave a healthy microbiota, the disease is morelikely to be severe.