The virus contaminated surfaces in less than 24 hours, despite the patients being pre-symptomatic, according to a study published in the journal Emerging Infectious Diseases.
Pre-symptomatic patients “may easily contaminate the environment,” the authors wrote.
To learn more about the pre-symptomatic spread of SARS-CoV-2 (the coronavirus which causes COVID-19), the researchers tested swabs taken from a hotel room where two Chinese students were quarantined. The students had been studying overseas. One, referred to as patient A, had returned on March 19 and patient B on March 20.
When they arrived in China, neither had a fever or any symptoms of COVID-19, but were taken to a hotel for a 14-day quarantine. Every morning and afternoon, local medical staff checked their body temperature and if they had developed symptoms. On day two, neither had a fever or symptoms. Regardless, they were tested for the coronavirus, and their results came back positive. They were sent to a local hospital for treatment, and still didn’t show any symptoms despite nose, sputum, and fecal samples testing positive and containing high levels of the SARS-CoV-2.
After two days in the hospital, patient A developed a fever and a cough. By day six, patient B had a fever and cough, and scans revealed issues with her lungs.
The researchers took swabs from surfaces in the students’ two hotel rooms three hours after they tested positive. They took samples from the pillow and duvet covers, sheet, and towel, as well as the door and faucet handles, light switch, the room’s thermometer, television remote, bathroom door handle, and toilet seat and flush. The students were the only people to recently stay in the room, as the hotel was closed from January 24 due to lockdown measures. To add a control to their study, the scientists also collected samples from an unoccupied room.
Out of the 11 samples they collected from each room (22 in total), eight were positive for the coronavirus. Six were from patient A’s room: on the sheet, duvet cover, pillow cases, and towel. The faucet of patient B’s room tested positive for the coronavirus, as well as the pillow case. As expected, the samples from the control room were negative for SARS-CoV-2. The pillow covers and sheet had a high viral load.
“In our study, we demonstrate high viral load shedding in presymptomatic patients, which is consistent with previous studies, providing further evidence for the presymptomatic transmission of the virus. In addition, presymptomatic patients with high viral load shedding can easily contaminate the environment in a short period.”
Prolonged contact with an object seemed to lead to higher levels of contamination, as the virus was found on a sheet and pillows but not the door handle and light switch, the team said.
The study highlights the importance of handling potentially contaminated bedding, they said. The researchers advised against shaking linens after stripping beds, to stop the virus spreading. Potentially contaminated items must be “thoroughly” cleaned and dried for the same reason.
In a previous study, the team showed that SARS-CoV-2 can linger in a household, after it was found in a kitchen and bedroom. That study was published in The Journal of Infectious Diseases.
Since the pandemic started late last year, the coronavirus has killed 323,345 people in more than 4.9 million document cases of COVID-19, according to Johns Hopkins University. Over 1.6 million people have survived. The U.S. is the country with the most known cases, as the graph below by Statista shows.
