We wear masks and we sanitise frequently. But how aware are we of the surfaces that we touch? A recent study done by the Australian Centre for Disease Preparedness suggests that perhaps we should make more of a concerted effort to keep up with handwashing and other steps to prevent the spread of Covid-19. The scientists have found that the virus is ‘extremely robust’, and can survive for nearly 30 days on various surfaces, including the glass of touchscreen phones and banknotes. If you think of the average excursion to the shops, one touches myriad surfaces without even thinking. You select your groceries off the shelf, touch the shopping cart and then whip your wallet out of your pocket/purse. While it may be exhaustingly laborious to sanitise after touching something, it may be necessary with certain items – especially when handling money or your cell phone. – Jarryd Neves
Coronavirus may stay for weeks on banknotes and touchscreens
By Jason Gale
(Bloomberg) — The new coronavirus may remain infectious for weeks on banknotes, glass and other common surfaces, according to research by Australia’s top biosecurity laboratory that highlights risks from paper currency, touchscreen devices and grab handles and rails.
Scientists at the Australian Centre for Disease Preparedness showed SARS-CoV-2 is “extremely robust,” surviving for 28 days on smooth surfaces such as glass found on mobile phone screens and plastic banknotes at room temperature, or 20 degrees Celsius (68 degrees Fahrenheit). That compares with 17 days survival for the flu virus.
Virus survival declined to less than a day at 40 degrees Celsius on some surfaces, according to the study, published in Virology Journal. The findings add to evidence that the Covid-19-causing coronavirus survives for longer in cooler weather, making it potentially harder to control in winter than summer. The research also helps to more accurately predict and mitigate the pandemic’s spread, the scientists said.
“Our results show that SARS-CoV-2 can remain infectious on surfaces for long periods of time, reinforcing the need for good practices such as regular hand washing and cleaning surfaces,” said co-author Debbie Eagles, the center’s deputy director, in an emailed statement Monday.
Read also: Inside Covid-19: Living through a pandemic – in SA, and in China. SAs speak – Ep 92
The coronavirus is transmitted mostly through direct contact with an infected person, especially the virus-laden particles they emit while coughing, sneezing, speaking, singing and even breathing. SARS-CoV-2 may also contaminate surfaces when these particles settle, creating so-called fomites that the researchers said may play a lesser, though important role in transmission of the virus.
“It does raise some critical issues around the need to keep on disinfecting surfaces, even when community cases are low,” said Trevor Drew, the center’s director and another co-author, in an interview. “We still need to carry out those disinfection regimes, both personally and at a public level, even when there don’t seem to be any cases around because there
may well be some residual virus that you’ve missed.”
SARS-CoV-2 spread via fomites is plausible, researchers at Kansas State University said in a study released ahead of publication and peer review in August. They analyzed the coronavirus’s stability on a dozen surfaces and found it survived five-to-seven times longer under cooler, less-humid spring/fall conditions compared with the average temperature and humidity in summer.
‘Big Surprise’
The finding bodes badly for controlling Covid-19 during the Northern Hemisphere winter, said virologist Juergen Richt, who led the research. “If we couldn’t control it very well during the summer, we are in for a big surprise,” Richt said in an interview.
Scientists at the Australian government laboratory have determined virus survival previously for hundreds of different viruses. They found in the case of SARS-CoV-2 that it survives longer on nonporous or smooth surfaces, compared with porous complex surfaces, such as cotton.
The research received funding from Australia’s defense department. It involved drying the coronavirus in an artificial mucus on different surfaces, at concentrations similar to those reported in samples from infected patients, and then re-isolating the virus over a month. The study was also carried out in the dark, to remove the effect of ultraviolet light, as research has demonstrated direct sunlight can rapidly inactivate the virus.
The time taken to achieve a 90% reduction in the amount of virus present on the surfaces studied under different temperatures is tabled below:
20 degrees Celsius | 30 degrees Celsius | 40 degrees Celsius | |
---|---|---|---|
Stainless steel | 5.96 days | 1.74 days | 4.86 hours |
Polymer note | 6.85 days | 2.04 days | 4.78 hours |
Paper note | 9.13 days | 4.32 days | 5.39 hours |
Glass | 6.32 days | 1.45 days | 6.55 hours |
Cotton | 5.57 days | 1.65 days | none recovered |
Vinyl | 6.34 days | 1.4 days | 9.9 hours |