Scientists using PCR found SARS-CoV-2 RNA in many places near infected people. In a Nebraska hospital, 65% – 82% of room surfaces, personal items, and toilets had SARS-CoV-2 RNA (Santarpia et al.). In hospitals in Wuhan, scientists found SARS-CoV-2 RNA on many surfaces in patient areas, ICUs, medical staff areas, and public areas. They suspected that when patients coughed and breathed, the virus-laden droplets and aerosols deposited on surfaces. Scientists also suspected that viruses moved from surfaces to the air, when people disturbed virus-laden droplet deposits on surfaces (Guo et al.; Liu et al.). Surfaces had viral RNA even in the rooms used by a patient with only mild upper respiratory symptoms, and in rooms without viral RNA in the air (Ong et al.). Hands touching these virus-laden surfaces could transfer viruses to nose, eyes, or mouth (Brosseau).
On one of the cruise ships having many infected passengers, scientists found SARS-CoV-2 RNA on many surfaces in rooms of both asymptomatic and symptomatic infected passengers 17 days after the passengers left. This shows that the viral RNA can remain there that long, maybe longer, but does not prove that this caused transmission (Moriarty et al.).
One research team spread viable SARS-CoV-2 viruses on surfaces, took samples from the surfaces after different time lengths, and cultured the viruses in cells to find if the viruses were still viable, a more thorough method than finding viral RNA. After 72 hours, the viruses were still viable on plastic and stainless steel, implying they might last longer. On cardboard, no viruses lasted longer than 24 hours, and some were not viable in even less time. On copper, no viruses lasted longer than 4 hours (National Institutes of Allergies and Infectious Diseases; van Doremalen et al.). Another set of experiments found SARS-CoV-2 lasted up to 3 hours on tissue and printing papers, 2 days on wood and cloth, 4 days on banknotes and glass, and 7 days on surgical masks, plastic, and stainless steel (Chin et al.). SARS-CoV-2 is generally less stable on surfaces at higher temperatures and humidity, but other factors probably more determine transmission (Chin et al., National Academies of Science 2020a).
This new coronavirus SARS-CoV-2 is about as stable on surfaces as the 2003 SARS-CoV virus (Bai et al.; van Doremalen et al.; Zou et al.). But the new virus is spreading to more people than SARS, probably because it creates more viruses inside infected people, and can transmit more from asymptomatic infected people to others (van Doremalen et al.).
In the Nebraska hospital described above, staff used powered air purifying respirators, N95 filtering facepiece respirators, and other personal protective equipment, and no staff were infected (Santarpia et al.). In Wuhan hospitals, scientists and medical staff found SARS-CoV-2 RNA on surfaces, cleaned them and their hands, sampled the surfaces again, and found no SARS-CoV-2 RNA. This shows that hand, face, and surface hygiene could probably stop transmission (Ong et al.). Many commercially available disinfectants and hand sanitizers can clean and inactivate this novel coronavirus SARS-CoV-2 (Center for Biocide Chemistries of the American Chemistry Council; Chin et al.; Kratzel et al.).
In Wuhan hospitals, scientists and medical staff found SARS-CoV-2 RNA in the air. Then they cleaned the surfaces, wore more personal protective equipment (PPE), and separated severe patients from moderately symptomatic patients in different wards or buildings. Then they sampled the air again, and found less airborne SARS-CoV-2 RNA, which shows that these actions might prevent aerosol transmission (Liu et al.).
Because of the many ways SARS-CoV-2 can stay on surfaces, if we are caring for a COVID-19 patient, we should wear a mask, and perhaps a clear face shield, not touch many surfaces in the patient’s room, wash our hands after each interaction with the patient, and wash or change clothes and shower after every few interactions with the patient. But if we go out in public or to a store with no known infected people, then we do not need to do all those precautions each time. We should, however wash hands after going out, and wipe packages (Centers for Disease Control and prevention 2020b; Food and Drug Administration; Herbst; Parker-Pope; Stump and Nguyen).