The virus responsible for Covid-19 can survive for up to 28 days on common surfaces such as banknotes and mobile phone screens, much longer than previously thought.
The study by Australia’s national science agency CSIRO found the virus survives longer at lower temperatures and on non-porous or smooth surfaces such as glass and stainless steel compared to porous surfaces such as cotton.
The virus can remain infectious for “significantly longer . . . than generally considered possible” on surfaces, which reinforces the need for good sanitation practices to mitigate its spread, according to the study, published in Virology Journal on Monday.
“This research shows that we need to continue to wash our hands and sanitise door handles, cutlery, cash machines and other commonly used surfaces,” said Trevor Drew, director of the Australian Centre for Disease Preparedness, which led the research.
However, he said the research was performed under “a worst-case scenario” method that probably extended the maximum length of time the virus could survive and remain infectious. For example, the research was conducted in the dark to negate the effects of ultraviolet light, which can kill the virus, and high viral loads were used, Mr Drew told the Financial Times.
An earlier study using a different methodology published in The Lancet in April found no infectious virus could be detected on glass or banknotes after four days or seven days for stainless steel.
Nevertheless, the CSIRO research provides important data that could inform disinfection procedures and highlight the potential infection risk posed by different surfaces and imported products. In August scientists in New Zealand suggested an outbreak of Covid-19 may have been linked to imported refrigerated freight.
Mr Drew said the ability of the virus to survive longer under cooler conditions might help to explain why nations faced a higher risk of Covid-19 outbreaks during winter.
The CSIRO study measured the survival rates of infectious SARS-CoV-2, the virus responsible for Covid-19, on several common surfaces at three different temperatures: 20C, 30C and 40C. It deployed viral loads broadly equivalent to the highest possible levels excreted by infectious patients.
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The virus remained present for up to 28 days on common surfaces such as glass, stainless steel, paper and polymer banknotes at temperatures of 20C. But the infectious virus survived less than 24 hours at 40C on some surfaces, the study found.
“At 20C, which is about room temperature, we found that the virus was extremely robust, surviving for 28 days on smooth surfaces such as glass found on mobile phone screens and plastic banknotes,” said Debbie Eagles, deputy director of the Australian Centre for Disease Preparedness.
“For context, similar experiments for influenza A have found that it survived on surfaces for 17 days, which highlights just how resilient SARS-CoV-2 is.”