Months after it first reared its head, the coronavirus continues to confound. A latest study has now found that the virus can survive for up to 28 days on common surfaces including banknotes and glass such as mobile phone screens and stainless steel.
The study conducted by researchers at the Australian Centre for Disease Preparedness (ACDP) also found that the virus survived longer at lower temperatures and on non-porous or smooth surfaces compared to porous, complex surfaces such as cotton.
It was also found to survive longer on paper banknotes than plastic banknotes. Establishing how long the virus remains viable on surfaces can help in predicting more accurately its spread and the ways to mitigating it.
It has so far been widely believed that the virus can survive for up to three days on solid surfaces. According to the World Health Organisation (WHO), coronavirus can survive for up to 72 hours on plastic and stainless steel; up to 24 hours on cardboard; and up to four hours on copper. This was also found in a study published in the New England Journal of Medicine.
Frequently touched surfaces such as door knobs and switches are among those that one has to be careful about. There has been a lot of speculation about the transmission of the virus through newspapers, courier packages and so on. The WHO has said that the risk of catching the virus from a package that has been moved, travelled, and exposed to different conditions and temperatures is low.
Experts consider surfaces not to be a major source of transmission of the disease, but with knowledge on the subject still evolving people are best advised to take precaution and sanitise surfaces and hands to stay safe.
The Centers for Disease Control and Prevention (CDC), a national public health institute in the United States, has also said that it is possible, though unlikely, to catch the virus from surfaces. CDC has said that a lot is still unknown about the virus and while it can survive for a short period on some surfaces, it is unlikely to be spread from domestic or international mail, products or packaging. “It may be possible that people can get Covid-19 by touching a surface or object that has the virus on it and then touching their mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads.”
The Australian body’s research involved drying virus in an artificial mucus on different surfaces, at concentrations similar to those reported in samples from infected patients, and then re-isolating it over a month. Further experiments were carried out at 30 and 40 degrees Celsius, with survival times decreasing as the temperature increased.
Similar experiments for Influenza A have found that it survived on surfaces for 17 days at 20 degrees Celsius, which highlights just how resilient SARS-CoV-2 is.
The study was also carried out in the dark to remove the effect of UV light as research has demonstrated direct sunlight can rapidly inactivate the virus.
“While the precise role of surface transmission, the degree of surface contact and the amount of virus required for infection is yet to be determined, establishing how long this virus remains viable on surfaces is critical for developing risk mitigation strategies in high contact areas,” Debbie Eagles, deputy director of ACDP, said in a press statement.
The study has also found that proteins and fats in body fluids can significantly increase the virus’s survival time. “This may explain the apparent persistence and spread of SARS-CoV-2 in cool environments with high lipid or protein contamination, such as meat processing facilities,” ACDP Director Professor Trevor Drew said.
The spread of Covid-19 from person to person is driven by droplet transmission that emerges from the mouth when a person speaks, coughs or sneezes. Infection can also happen when a person touches a surface or object that has the virus on it and then touches the eyes, nose or mouth.