In a study of 15 coronavirus patients, which was conducted by the Chinese University of Hong Kong and published in the medical journal Gut, researchers found that close to half of the subjects tested positive for the virus in stool samples—including patients with no stomach-related symptoms such as nausea or diarrhea. The researchers found that the same patients continued to test positive via their stool for a week after their respiratory tests came back negative, Bloomberg reports. In fact, study co-author Siew Chien Ng, assistant dean of medicine and associate director of the university’s Centre for Gut Microbiota Research, told the outlet one patient was still positive 30 days later. “We used to think of SARS-CoV-2 as just a pulmonary or respiratory disease,” Ng told Bloomberg. “But over the last couple months, a lot of evidence has emerged that SARS-CoV-2 also affects the intestinal tract.” While medical experts now widely agree that COVID-19 is transmitted mainly through droplets spread into the air by talking, coughing, or sneezing, the study’s findings support mounting evidence that the digestive system can also play a part in the passage of the virus through humans.ae0fcc31ae342fd3a1346ebb1f342fcb Other investigations have shed light on the possibility of coronavirus being spread via the intestinal tract. A report released in August found that a long-vacant apartment in Guangzhou, China, had been infected with COVID-19 particles via plumbing from another unit in the building where five people had the virus. And another recent study found that two residents of a Hong Kong apartment building contracted the coronavirus in February through an unsealed pipe in the bathroom of one of the infected tenants, despite living 10 floors apart from each other. The Centers for Disease Control and Prevention (CDC) also published relevant research in their journal Emerging Infectious Diseases, confirming that it’s possible COVID could be transmitted this way. “Isolation of infectious SARS-CoV-2 in feces indicates the possibility of fecal-oral transmission or fecal-respiratory transmission through aerosolized feces,” the CDC wrote in an August report. RELATED: For more up-to-date information, sign up for our daily newsletter. These discoveries have led to major innovations in identifying potential outbreaks, including the use of sewage treatment plants to pinpoint new COVID hotspots. Additionally, this possibility can make it easier and safer to screen certain parts of the population for coronavirus—especially infants, young children, and the elderly, where getting a respiratory sample can be difficult or dangerous. And for more on how COVID stays with you, check out The 98 Longest Lasting COVID Symptoms You Need to Know About.