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Researchers from the Australian Center for Disease Preparedness have shown that SARS-CoV-2 is “extremely resistant” and can survive on flat surfaces such as mobile phone screens and banknotes for up to 28 days at room temperature or 20 degrees Celsius. For example, the flu virus only survives for 17 days.
According to a study published in Virology Journal on Monday, the survival of the virus dropped to less than a day when the surface temperature was 40 degrees Celsius. These findings complement previous evidence that the coronavirus that causes Covid-19 survives longer in colder climates and may be more difficult to control in winter than in summer.
The study also helps more accurately predict and mitigate the spread of the pandemic, the researchers said.
“Our results show that SARS-CoV-2 can remain contagious on surfaces for a long time, which means that strict hygiene, such as washing hands and cleaning surfaces, must be maintained regularly,” he said. Debbie Eagles, deputy director of the center, highlighted in the report.
The coronavirus is usually transmitted through direct contact with infected people, mainly through particles loaded with the virus, which they secrete when coughing, sneezing, talking, singing and even breathing. SARS-CoV-2 can also contaminate surfaces when these particles settle on them, creating the so-called phomit, which according to scientists “can also be an important factor in the transmission of the virus.”
Although this has yet to be proven, SARS-CoV-2 is likely to spread in phomit, researchers at Kansas State University noted in a study published before an Australian study and a peer review in August.
They analyzed the stability of the coronavirus on a dozen surfaces and found that it survived five to seven times longer in cooler and less humid spring and fall weather conditions compared to average summer temperature and humidity.
The discovery means that controlling Covid-19 in the northern hemisphere during winter will be a serious challenge, said Juergen Richt, the virologist who led the study.
“Big surprise”
“If we couldn’t successfully control the virus even in the summer, we are in for a big surprise,” Richt said in an interview.
Researchers at the Australian Government Laboratory have found that the coronavirus stays longer on smooth or non-porous surfaces compared to complex porous surfaces like cotton.
The study received funding from the Australian Department of Defense. The coronavirus was dried into artificial mucus on different surfaces at roughly the concentration found in samples from infected patients and then re-isolated for a month.
The study was conducted in the dark to eliminate the effects of ultraviolet light, as studies have shown that direct sunlight can rapidly inactivate the coronavirus.
Below is the time it takes for 90 percent. the amount of virus present on the test surfaces at different temperatures (20 ° C, 30 ° C and 40 ° C) decreases:
Stainless steel: 5.96 days, 1.74 days and 4.86 hours
Polymer ticket: 6.85 days, 2.04 days and 4.78 hours
Paper ticket: 9.13 days, 4.32 days and 5.39 hours
Glass: 6.32 days, 1.45 days and 6.55 hours
Cotton: 5.57 days, 1.65 days, did not survive
Vinyl: 6.34 days, 1.4 days and 9.9 hours
“Although the exact role of surface transmission, the degree of exposure and the amount of virus required for infection have yet to be determined, measuring how long the virus remains viable on surfaces is a critical step in developing reduction strategies. of hazards in areas of frequent contact, “Eagles said.
Transmission risk
The survival of the virus in glass is an important finding, as touch-screen devices such as mobile phones, ATMs, supermarket checkouts, and airport check-in kiosks are frequent contact surfaces that may or may not be cleaned regularly, which leads to SARS. The risk of CoV-2 transmission, the researchers said.
They found that the survival time of SARS-CoV-2 on banknotes is longer than that of seasonal influenza, which is “particularly important given the frequency of circulation and the potential for transmission of the virus not only between individuals but also between geographic locations “.
Even before the announcement of the SARS-CoV-2 pandemic, China began to disinfect its paper money, suggesting that concerns about the transmission of the virus to banknotes already existed at that time, scientists say, noting that states The United States and South Korea also quarantined their banknotes as a result of the pandemic.
According to the study authors, survival of the coronavirus on stainless steel surfaces at cooler temperatures may help explain the Covid-19 outbreaks associated with meat processing and storage facilities. Their data supports the findings of a study showing the survival of SARS-CoV-2 in fresh and frozen foods.
“The study may also help explain the resistance and spread of SARS-CoV-2 in cold environments with high levels of lipids or proteins, such as in meat processing plants, and consider how we can better manage this risk,” said Trevor Drew in a statement. Director of the Australian Center for Disease Preparedness.
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