The coronavirus that causes the COVID-19 pandemic can, in cool, dark surroundings, survive for up to 28 days on surfaces such as phones and banknotes, according to a study by the Australian National Science Agency (CSIRO).
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Researchers from the CSIRO’s disease prevention department have found that the warmer the temperatures, the lower the survival rate of SARS-CoV-2, the agency revealed on Monday.
They found that at 20 degrees, SARS-CoV-2 is “extremely resistant” on smooth surfaces, such as telephone screens. It can survive 28 days on glass, steel and polymer banknotes.
At 30 degrees, that survival rate drops to 7 days, and at 40 degrees, it’s only 24 hours.
On porous surfaces like cotton, the virus survived shorter, up to 14 days at the lowest temperature and less than 16 hours at the highest.
Compared to previous studies, which had shown that the coronavirus could survive for up to four days on non-porous surfaces, this time is “significantly longer,” according to the Journal of Medical Virology.
Trevor Drew, director of the Australian Center for Disease Prevention, explained that the study consisted of drying samples of the virus on different materials before testing them with an “extremely delicate” method. It has made it possible to find traces of living virus capable of infecting cell cultures.
However, “this does not mean that this amount of virus could infect someone,” he said on the public channel ABC.
However, if a person “careless with these materials touched them, then licked your hands or touched your eyes or nose, you could be infected more than two weeks after they were contaminated.”
Mr Drew expressed reservations, not least because this study was conducted with fixed levels of the virus, probably corresponding to the peak of an infection, and in the absence of exposure to ultraviolet light that can quickly alter the virus.
Humidity was kept at 50%, according to the study, because a rise in humidity is also bad for the virus.
According to the CSIRO, the virus is mainly spread through the air, but more research is needed to better understand how it is transmitted through surfaces.
Mr. Drew recalled that the main message is that “contaminated people are much more contagious than surfaces”.
“This can nevertheless help explain why, even when there are no more contagious people, it happens that (the epidemic) comes back even if the country is considered to be free of the virus,” he said.