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Researchers say the novel coronavirus can survive for weeks in cool temperatures and dark surroundings. Cavan Images/Getty Images
  • Researchers say the novel coronavirus can live up to 28 days on surfaces in cool and dark circumstances.
  • In another study, researchers said the virus can live up to 9 days on human skin.
  • Experts say these studies emphasize the need for people to wash their hands and clean surfaces.

Cooler temperatures, limited light, and a comfortable surface may feel like home sweet home to the novel coronavirus, SARS-CoV-2.

Research published in the Virology Journal by Australia’s national science agency, CSIRO, is reporting that SARS-CoV-2 can survive for as long as 28 days on surfaces such as plastic, glass, steel, vinyl, and even paper.

A second study published in early October in the journal Clinical Infectious Diseases found that the virus can live on human skin for up to 9 hours.

There are two caveats, though. The first study was done entirely in the dark, and the second found that hand sanitizer or soap and water killed the virus on skin.

Still, epidemiologists say they’re surprised at the length of time the virus stayed robust and active in each study.

In comparison, the flu virus lasts on surfaces for 17 days and on skin for about 2 hours.

“The fact that [the novel coronavirus] can even survive on a surface that long proves that it is risky,” Thomas A. LaVeist, PhD, dean of the School of Public Health and Tropical Medicine at Tulane University in Louisiana, told Healthline. “28 days is a long period of time.”

Trevor Drew, PhD, director of the Australian Centre for Disease Preparedness and a lead author of the first study, told Healthline the long survival time of the virus surprised his team.

“We were certainly somewhat surprised at the length of time the virus survived at 20 degrees Celsius (68 degrees Fahrenheit),” Drew said.

“We knew from other coronaviruses, such as PED, that the virus can survive at ambient temperature for long periods, but past studies of SARS CoV-2 had indicated lesser survival times,” he added.

Drew said the study looked closely at temperature changes and found that as the temperature increases, the virus loses its power and dies off more quickly.

They placed the virus on surfaces at 20, 30, and 40 degrees Celsius and checked it for potency.

For instance, he said, “We conclude that, depending on the material, a change in temperature of between 12 degrees Celsius and 18 degrees Celsius will achieve a 10-fold change in the decimal reduction time.”

As an example, he said a virus deposited on a stainless steel door handle in an abattoir (slaughterhouse) at an inside temperature of 6 degrees Celsius could last 10 times longer than at 20 degrees Celsius.

“The effect of temperature is also likely to be seen in virus aerosols,” Drew added. “The virus would survive longer in cold air than in warm air, in absence of UV light.”

The study found that the virus survived longest on surfaces like plastic and steel, a bit less on paper, and significantly less on a soft cotton surface.

The second study, conducted by Kyoto Prefectural University of Medicine in Japan, reported that the novel coronavirus remained infectious on skin for as long as 9 hours.

“This study shows that SARS-CoV-2 may have a higher risk of contact transmission [i.e. transmission from direct contact] than IAV [influenza A virus] because the first is much more stable on human skin [than the latter],” the researchers wrote.

What can the public do with this new information?

The Kyoto researchers wrote, “These findings support the hypothesis that proper hand hygiene is important for the prevention of the spread of SARS-CoV-2.”

LaVeist said the results are a call to action for the public to “double down” on everything they’re doing to fight the spread of the virus.

“It does not change what we need to do,” he said. “It may just change the frequency and intensity.”

LaVeist said restaurants and public places, as well as people at home, should continue handwashing, masking, and physical distancing but also consider regular and vigorous cleaning of surfaces.

“We’ve got to start thinking about this immediately,” he said. “Tables, surfaces in classrooms. We should already be doing this. But this reaffirms the need.”

Experts believe the main way the virus is spread is through airborne droplets.

However, the World Health Organization has also said that it can be spread when someone touches something with droplets on it and then touches their face or mouth.

Drew agreed.

“This study emphasizes the ongoing importance of washing hands, using hand gels/wipes when out in public,” he said. “Avoid touching common surfaces whenever possible and don’t put your fingers in your mouth or rub your eyes.”

And what of past studies that concluded the virus only lasts a handful of hours on surfaces?

LaVeist said the public needs to understand that this is how investigative science works.

“This is the sausage-making in public view,” he said. “[Researchers] are constantly looking for something we can disprove as fact.”