The study said the items — chosen for their prevalence in public areas, such as hospital rooms and public transport, as well as high-contact surfaces like cellphones or ATMs — were tested at temperatures of 20C, 30C and 40C.
“These findings demonstrate SARS-CoV-2 can remain infectious for significantly longer time periods than generally considered possible,” read the study, which was published in the peer-reviewed Virology Journal.
How much a material was warmed had a dramatic effect on the virus’ shelf life, the study said.
Researchers found that the virus was still detectable 28 days later on glass, plastic bills, stainless steel, vinyl and paper currency that was heated to 20C but only lingered for up to 9.1 days on cotton cloth materials.
That number dropped to seven days for stainless steel, plastic notes and glass that was heated to 30C, and three days for vinyl and cotton cloth.
“At 40C, virus recovery was significantly reduced” to up to 48 hours, the study read, including all surfaces except cotton cloth, which saw no traces of the virus after 24 hours.
Their results contradict earlier research published in the Lancet, which concluded in May the virus could live for up to six days on stainless steel or plastic and up to three days on banknotes and glass.
In May, the U.S. Centers for Disease Control and Prevention said that a person was more likely to catch COVID-19 from standing in close proximity with someone than from contaminated surfaces.
“The virus does not spread easily in other ways,” including by touching surfaces, the agency said.
“But that doesn’t mean touch is zero-risk. It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes. This is not thought to be the main way the virus spreads, but we are still learning more about this virus,” the CDC wrote.
Dr. Alon Vaisman, an infection control and infectious disease physician at the University Health Network in Toronto, said the point is simple: “Wash your hands.”
The risk of transmission from surface contamination is unlikely to be a major driver in COVID-19 cases, he said, adding confirmed cases were more likely to be driven up from “superspreader events” such as in-person church services.
Notably, the study did not expose any of the surfaces they tested to UV rays. Vaisman said the virus is easily “inactivated” by sunlight, which is why COVID-19 is less prevalent in outdoor settings.
The surfaces tested had no insulation from the virus either, which he said was unrealistic, as surfaces in places like hospitals, schools and on public transportation are regularly cleaned.
But even if a surface was contaminated, Vaisman said, “it’s relatively easy to kill the virus.”
COVID-19 can survive up to nine hours on a person’s hands, but “it’s very, very easily killed with alcohol,” he said.
“Even if it’s a small component, people are still going to clean surfaces regularly, routinely, and we’re going to continue doing that at hospitals, for example,” said Vaisman.
“Even if it survives for days, if you’re washing your hands, it can’t possibly infect you.”
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