A study of eight patients found that the lung microbial composition of COVID-19 patients is primarily made up of bacteria typically found in the oral and upper respiratory tract. It is thought that the gut microbiota plays an important role in buttressing antiviral immunity and has been shown to reduce viral-related enteritis, severe pneumonia cases that require ventilator assistance, and can prevent the spread of influenza in lung epithelia cells. No clinical data suggest that modulating the gut microbiota is an effective treatment for COVID-19, but it may be a relevant therapeutic target.