The novel coronavirus may be present on surgical masks for up to seven days after exposure, new evidence suggests. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the coronavirus disease (COVID-19), also appears to be affected by high temperatures.
Researchers cultured and incubated the virus for up to two weeks before testing its stability, or how long it persists on a surface, to determine how infectious it is under different temperatures and environmental conditions. The virus was found to be highly stable at a temperature of 4°C (39.2°F), yet appears to be sensitive to high heat, rendering it inactive within five minutes of being exposed to a temperature of 70°C (158°F).
To determine its stability on different surfaces, the researchers then used a pipette to place the virus on cardboard, paper, plastic, and other materials and left it at a room temperature of 22°C (72°F) with a humidity of about 65 percent.
No infectious virus was found on printing or tissue paper after three hours, yet it took two days for it to no longer be detected on wood and cloth. On the other hand, SARS-CoV-2 is more stable on smooth surfaces – it took up to four days for the virus to lose its presence on glass and money and it persisted on stainless steel and plastic for a week.
“Strikingly, a detectable level of infectious virus could still be present on the outer layer of a surgical mask on day 7,” write the study authors in The Lancet. However, because of the way the virus was administered, the findings do not necessarily depict how easy it is to potentially “pick up the virus from casual contact.”
Although the virus can be “highly stable in a favorable environment,” the researchers found that it is susceptible to standard disinfection methods and can generally be removed at room temperature within five minutes. The Centers for Disease Control and Prevention (CDC) advises people to use approved disinfectants to kill germs on surfaces, particularly areas of the house that are frequently touched like tables, doorknobs, light switches, toilets, and electronics.
Much is yet to be discovered about SARS-CoV-2 and what is known changes frequently. Previous research found that the virus is detectable on copper for up to four hours after contamination and up to 24 hours on cardboard, but the virus is believed to degrade quickly on most surfaces. The SARS-CoV-2 virus was also shown to be present in the air in an aerosolized form for up to three hours, though researchers are quick to advise that this does not necessarily mean it can be transmitted through inhaling infected air.