While COVID-19 was first identified because of its effect on the respiratory tract, doctors began to notice that some patients suffering mild cases of the virus experienced digestive symptoms including diarrhea, nausea and vomiting. These have now been documented in multiple studies. One group of researchers estimated that symptoms were present in 3% to 39% of COVID-19 patients studied.
Data about 116 patients at Stanford Medical Center in California found that 31.9% of patients reported "mild" symptoms: 22% reported a loss of appetite, 22% had nausea and vomiting and 12% had diarrhea. Stanford doctors suggested the results showed the importance of testing more widely in patient populations for the presence of the coronavirus.