This study examined the survival and infectivity of SARS-CoV-2 (COVID-19) and SARS-CoV-1 in air and on solid surfaces. A concentration in the same ballpark as the amount coughed out by an infected person was incorporated into aerosolised droplets which were either kept inside an enclosed drum for 3 hours, or were deposited onto stainless steel, polypropylene plastic (the type used to make drinking water bottles), copper or cardboard for 4 days. Virus survival and ability to infect were examined under controlled laboratory conditions; 21 – 23°C and 65% humidity.
After 3 days the levels of SARS-CoV-2 on plastic were so low virus could no longer be detected. SARS-CoV-2 survived for 2d on stainless steel, 1 day on cardboard and only 8h on copper. After 3 hours there was only a slight decrease in infectious titre in air, from 103.5 to 102.7 TCID50 per litre of air. SARS-CoV-1 had similar survival and infectivity to SARS-CoV-2.
A key point is that both viruses were still infectious after 3h in still, enclosed air, and about 6h after being deposited onto solid surfaces like stainless steel or plastic. Disinfection of solid surfaces in labs, treatment plants and offices will remove viruses, but if a COVID-19 infected person coughs in an enclosed work-space, thought should be given to circulating and replenishing the air to reduce the risk of transmitting infection.
Neeltje van Doremalen, Trenton Bushmaker, Dylan H. Morris (2020) Letter to the Editor of the New England Journal of Medicine, published on March 17, 2020