“Yes,” says Brian Lacy, MD, PhD, a gastroenterologist and a professor of medicine at the Mayo Clinic in Jacksonville, Florida. “We understand that COVID can affect the gastrointestinal (GI) tract, leading to symptoms of nausea, vomiting, abdominal fullness or pressure, bloating, and diarrhea. In fact, there are more COVID receptors in the GI tract than in the lungs. We now recognize that a COVID infection is one cause of persistent diarrhea. We also now recognize that COVID is shed from the GI tract.” While hand-washing won’t stop the coronavirus from spreading via coughs or sneezes, it can make a big difference in stopping the spread when it is present in the GI tract. “When someone doesn’t wash their hands well or there’s fecal matter trapped under the fingernails, it may carry a viral load that can easily spread to other people,” says Rabia De Latour, MD, a gastroenterologist and an assistant professor of medicine at NYU School of Medicine in New York City. “That’s why we see a high prevalence of COVID-related GI symptoms among children.” A study published in the American Journal of Gastroenterology in January 2022 found that nearly 60 percent of hospitalized COVID-19 patients complained of GI symptoms. “When it penetrates the gut lining, it can spread to the gut-lung axis, and most severe cases that we’re seeing are related to gut involvement,” says Brennan Spiegel, MD, a gastroenterologist and researcher at Cedars-Sinai in Los Angeles. “We’ve seen an uptick in sepsis from bacteria due to COVID. When the gut lining becomes leaky or permeable, we see bacteria leaking into the body, getting into the system, and that causes problems.”
Are Some People More Susceptible to GI Symptoms Than Others?
Dr. Spiegel said that he did not know of any particular population that was more susceptible to COVID-related GI symptoms, but added that there is debate within the professional community about whether there should be increased concern for patients who do not have acid in their GI system. Otherwise, research has focused on the gut microbiome’s role in tamping down inflammation that runs from the gut to the lungs. New research suggests there is an axis of communication where intestinal microbial communities have a profound effect on lung disease, according to an analysis in the February 2020 Frontiers in Cellular and Infection Microbiology. An October 2021 review in Frontiers in Immunology looked into the possibility that targeted therapy for the gut microbiome can prevent the leaky gut phenomenon that allows bacteria to permeate the lining of the intestine and enter the circulatory system. The health of the gut microbiome — variety and quantity — has emerged in research as an indicator of better COVID-19 outcomes. Both a study published in March 2021 in Gut and a study published in January 2022 in BMC Medicine compared the gut flora of people infected with COVID-19 and people who weren’t. Those who were not infected or had better outcomes had more gut flora, a higher concentration of microbes that boosted immunity, and greater bacterial diversity in their gut. Those who fared worse or were more susceptible to “long COVID” had a less-diverse microbiome and a greater concentration of harmful bacteria. A study published in Gut in January 2022 found that people who suffered from long COVID had their gut microbiome altered by the disease for over six months after COVID-19 left their system. Patients who had lingering respiratory symptoms showed increased levels of a bacterium known to attack the gut-lung axis, while people with depression or fatigue had greater concentrations of gut bacteria associated with those conditions. “The gut houses the largest organ of the immune system, so it’s no surprise that the health of the microbiome will influence the immune response to SARS-CoV-2,” says Dr. De Latour. “It could be the increased immunity from vaccines coupled with the changes in the virus, but we’re not seeing the severe manifestations and catastrophic outcomes that we first saw,” Spiegel says. “We’re not seeing overwhelming sepsis as frequently as we did at the beginning of the pandemic.” He added that while the severity of GI symptoms has diminished, there has been a nationwide uptick in irritable bowel syndrome (IBS) cases. “We’re seeing cases where people are left with IBS long after COVID seems to have disappeared,” says Spiegel. “And while we’re seeing an increase in prevalence across the population, we don’t have the data to say it’s from COVID. It could be stress, or something we haven’t pinpointed yet.” While the frequency of severe GI complications has declined, a paper published in the Lancet Gastroenterology and Hepatology in May 2021 noted that severe cases of COVID-19 often lead to severe GI complications, including acute liver injury, elevated enzyme levels, acute pancreatitis, and an inability to eat. The review also highlighted some long-term effects, including loss of appetite, frequent bouts of diarrhea, or persistent nausea. But researchers have more to learn. “In a small subset of patients, a COVID infection can lead to the development of irritable bowel syndrome,” says Dr. Lacy. “This would be called a postinfection IBS state. We also now recognize that COVID can affect the liver and lead to liver test abnormalities and, rarely, more serious complications.” He also points out that physicians are just learning how different virus variants can affect the GI tract. “More data will be coming out in the next few years.”
