MELBOURNE/SYDNEY • The virus that causes Covid-19 can survive on banknotes, glass and stainless steel for up to 28 days, much longer than the flu virus, Australian researchers said yesterday, highlighting the need for cleaning and hand washing to fight the coronavirus.
Findings from the study by Australia's national science agency, the Commonwealth Scientific and Industrial Research Organisation (Csiro), appear to show that in a very controlled environment, the virus was infectious for longer than other studies have found.
Csiro researchers found that at 20 deg C, the Sars-Cov-2 virus remained infectious for 28 days on smooth surfaces such as plastic banknotes and glass found on mobile phone screens. The study was published in Virology Journal.
By comparison, the influenza A virus has been found to survive on surfaces for 17 days.
Lead researcher Shane Riddell said: "It really reinforces the importance of washing hands and sanitising where possible."
Professor Paul Digard, a virology specialist at Britain's Edinburgh University Roslin Institute, said it was significant that the researchers had measured infectious virus, not just detectable bits of virus, but added that it was also key to remember the virus' infectivity decays over time.
"So the amount of virus surviving at 28 days is very low and is therefore likely to be much less likely to infect someone than the higher amounts present when the virus is freshly deposited," he said.
The study involved drying the virus in an artificial mucus on a range of surfaces at concentrations similar to samples from Covid-19 patients and then recovering the virus over a month.
Experiments carried out showed that the virus survived longer at cooler temperatures, longer on smooth surfaces than on complex surfaces like cotton, and longer on paper banknotes than on plastic banknotes.
The persistence on glass is an important finding, given that touchscreen devices such as mobile phones, bank ATMs, supermarket self-serve check-outs and airport check-in kiosks are high touch surfaces which may not be regularly cleaned and therefore pose a transmission risk of Sars-Cov-2, the researchers said in the paper.