Researchers have said that Covid-19 (SARS-Cov-2), which causes the new coronavirus infection, can survive for 28 days on smooth surfaces such as stainless steel, phone screens, glass, plastic, and banknotes.
Contrary to previous research suggesting that Covid-19 can survive three to seven days on smooth surfaces, the recent study by researchers from the Australian agency CSIRO says the virus can remain infectious for up to 28 days, longer than the virus from the flu. when kept in the dark at room temperature (degrees Celsius [68 Fahrenheit]).
This research article was published in Virology Journal on October 7.
WHAT DOES THE RECENT STUDY SAY?
According to the study, at 20 degrees Celsius, the infectious virus Covid-19 or SARS-CoV-2 was still detectable after 28 days “after inoculation, for all non-porous surfaces” tested during the experiment: glass, note of polymer, steel notes of steel, vinyl and paper.
“With initial viral loads broadly equivalent to the highest titers excreted by infectious patients, viable virus was isolated for up to 28 days at 20 degrees Celsius from common surfaces such as glass, stainless steel, and paper and polymer banknotes,” he said.
In its conclusion, the paper stated: “These findings demonstrate that SARS-CoV-2 can remain infectious for significantly longer periods of time than is generally considered possible. These results could be used to inform improved risk mitigation procedures for prevent the spread of Covid-19 fomites. “
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By comparison, influenza A virus has been found to survive on surfaces for 17 days.
It also revealed that the virus survived longer on smooth surfaces than on complex surfaces like cotton, and longer on paper banknotes than on plastic banknotes.
The experiment was carried out in a highly controlled environment, in a “high containment laboratory (biosafety level 4)” at the Australian Center for Disease Preparedness, in the dark, to eliminate the impact of ultraviolet (UV) light. .
It involved drying the virus in artificial mucus on a variety of surfaces at concentrations similar to those in samples from Covid-19 patients and then recovering the virus for a month.
So, to prevent contagion, the study’s lead researcher, Shane Riddell, said it’s important to clean surfaces that may be in contact with the coronavirus and wash and disinfect your hands regularly.
Reuters quoted Shane Riddell as saying: “It really reinforces the importance of hand washing and sanitizing where possible and certainly cleaning surfaces that may be in contact with the virus.”
DIFFERENCES AND SIMILARITIES WITH THE LANCET STUDY
A study published in The Lancet magazine in May revealed that when kept at room temperature, “no infectious virus could be detected on the smooth surfaces treated on day 4 [glass and banknote] or day 7 [stainless steel and plastic]. “
For surfaces that are not smooth, the study said: “No infectious virus could be recovered from printing papers and tissue after a 3-hour incubation, while no infectious virus could be detected on wood and fabric. treated on day 2 “.
In the case of surgical masks, the study showed that “a detectable level of infectious virus could still be present in the outer layer of a surgical mask on day 7.” [~0·1 per cent of the original inoculum]”.
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This lancet was performed under the following conditions: a virus culture drop (~ 7-8 log units of TCID50 per ml) was poured onto a surface and left at room temperature (22 degrees Celsius) with a relative humidity of around 65 percent.
Even though the two studies differ in the number of days for which the Covid-19 or SARS-CoV-2 virus remains infectious, they both showed that Covid-19 or SARS-CoV-2 was more stable on smooth surfaces.
THE VIRUS IS SENSITIVE TO HEAT
Both studies have proposed that the virus cannot survive any longer when the temperature rises.
At 20 degrees Celsius, the virus survives for 28 days. When the temperature rises to 30 degrees Celsius, the survival rate drops to 7 days and to 40 degrees, it is reduced to just 24 hours, revealed the study by Australian researchers.
“The infectious virus survived less than 24 hours at 40 degrees Celsius on some surfaces,” said the Virology Journal research article.
While the Lancet study said that the virus stopped being infectious in just 5 minutes when the temperature rose to 70 degrees Celsius.
“With the incubation temperature increased to 70 degrees Celsius, the inactivation time of the virus was reduced to 5 minutes,” he said.
“The virus is very stable at 4 degrees Celsius,” the Lancet study said.
Referring to the upcoming southern hemisphere summer, Riddell said: “Going into summer, it will certainly be an important factor that the virus does not last as long in warmer temperatures.”
(With input from Reuters)
