COVID-19 patients with no symptoms are as likely as those with symptoms to contaminate many surfaces in their rooms, researchers report.
The investigators sampled the surfaces and air of six negative pressure non-intensive care unit rooms with 13 laboratory-confirmed COVID-19 patients -- two of whom had no symptoms -- who had returned from overseas and were in an isolation ward in Chengdu, China. In a negative pressure room, a machine pulls air into the room and then filters that air before moving it outside.
Samples were collected from surfaces such as bedrails, door handles, light switches, foot flush buttons, sink rims, sink and toilet bowls and drains, bedside tables, bedsheets, pillows, equipment belts on the wall, floors and air exhaust outlets.
Of the 112 surface samples collected, 44 (39.3 percent) were positive for the new coronavirus (SARS-Cov-2). All of the air samples were found to be negative, according to the study published June 24 in the journal mSphere.
"In a single room with an asymptomatic patient, four sites including bedrail, pillow, bedsheet, and the air exhaust outlet were SARS-CoV-2-positive," the researchers wrote. "This highlights that asymptomatic COVID-19 patients can contaminate their surroundings and therefore make persons who have direct contact with them such as their family members and health care workers be exposed to SARS-CoV-2," they said.
The findings also show the importance of thorough cleaning of areas occupied by COVID-19 patients, the researchers said.
"Placement of COVID-19 patients in rooms with negative pressure may bring a false feeling of safety, and rigorous environment cleaning should be emphasized," study author Dr. Zhiyong Zong, from the Department of Infection Control at West China Hospital, said in a journal news release.
Also, the study found "that patient surroundings in this non-ICU negative pressure isolation ward for COVID-19 patients with mild disease or no symptoms were extensively contaminated by SARS-CoV-2," Zong and colleagues wrote.
The results suggest that isolation of asymptomatic COVID-19 patients at home may put their families at risk, and that shelter hospitals may be a better option, the authors said.