The results of Australian researchers on the SARS-CoV-2 virus increase the need for hand washing and effective cleaning.
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 Monday, stressing the need for effective cleaning and hand washing to fight the disease.
The results of the study by the Australian national science agency CSIRO appear to show that the virus remained infectious longer than other studies in a strictly controlled environment.
CSIRO researchers said the SARS-COV-2 virus was “extremely robust” at 20 degrees Celsius and remained infectious for 28 days on smooth surfaces such as plastic banknotes and glass on cellphone screens. The study was published in the Virology Journal.
In comparison, the influenza A virus was found to survive on surfaces for only 17 days.
“It really highlights the importance of washing and disinfecting hands where possible and wiping surfaces that may come in contact with the virus,” said lead researcher on the study, Shane Riddell.
The study involved drying the virus in an artificial slime on a number of surfaces at concentrations similar to samples from COVID-19 patients and then recovering the virus for a month.
Experiments at 20, 30 and 40 degrees Celsius showed that the virus survived longer at cooler temperatures, on smooth surfaces and on paper banknotes than on plastic banknotes.
The researchers said they couldn’t detect a viable virus on a cloth at 20 degrees after 14 days. At 30 degrees, virus viability on cotton dropped to just three days, compared to seven days on steel and smoother surfaces. Viability continued to drop at 40 degrees Celsius.
All experiments were done in the dark to eliminate the influence of ultraviolet light, as research has shown that direct sunlight can kill the virus.
“In the real world, the results would probably be shorter than what we could show,” Riddell told Reuters.
A new study by the Australian National Science Agency shows that the coronavirus that causes COVID-19 can survive longer on paper banknotes than on plastic banknotes [William West/AFP]Julie Leask, a professor at the Susan Wakil School of Nursing and Obstetrics in the Faculty of Medicine and Health, University of Sydney, said the results were useful but needed to be put into perspective.
“The study usefully confirms that surfaces can be a way to pass on the coronavirus, but we should look to epidemiology to see how it actually moves between people in everyday life,” Leask wrote on Twitter. “These data show that there is still close contact with an infected person who is risky and does not touch a cellphone 5 days later.”
The infectious dose of SARS-CoV-2 is not yet known, but based on related viruses, it is believed to be around 300 particles. Researchers said that if the virus were placed on smooth surfaces at an infected person’s standard mucus concentration, “enough virus would easily survive two weeks to infect another person.”
CSIRO noted that the infection would depend on a number of factors, including the makeup of the virus itself, the nature of the surface, and whether the virus is liquid or dry.
The study could also help explain the apparent persistence and spread of the virus in cool environments such as meat packing plants.