The coronavirus that causes Covid-19 can adhere to stainless steel and plastic surfaces for up to four days, and to the outer layer of a face mask for a week, according to a study by researchers from the University of Hong Kong (HKU).
The team also found that common household disinfectants, including bleach, were effective in “killing” the virus.
The findings, published in a letter in medical journal The Lancet Microbe on Thursday (April 2), add to a growing body of research about the stability of Sars-CoV-2 – as the coronavirus is formally known – and what can be done to prevent its transmission.
“Sars-CoV-2 can be highly stable in a favourable environment, but it is also susceptible to standard disinfection methods,” said the researchers, who included, from HKU’s school of public health, Leo Poon Lit-man, head of the public health laboratory sciences division, and Malik Peiris, a clinical and public health virologist.
The researchers tested how long the virus could remain infectious at room temperature on a variety of surfaces.
On printing and tissue paper it lasted less than three hours, while on treated wood and cloth — a standard cotton laboratory jacket — it had disappeared by the second day.
On glass and banknotes the virus was still evident on the second day, but had gone by the fourth, while on stainless steel and plastic it was present for between four and seven days.
“Strikingly,” the researchers said, there was still a detectable level of infection on the outer layer of a surgical face mask after seven days.
“This is exactly why it is very important if you are wearing a surgical mask you don’t touch the outside of the mask,” Mr Peiris told the South China Morning Post. “Because you can contaminate your hands, and if you touch your eyes you could be transferring the virus to your eyes.”