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Australian researchers have sprayed pieces of glass and stainless steel, as well as banknotes with virus solution, and have checked how long the pathogen remains infectious there. The span of time was unexpectedly long.
The new coronavirus can survive for up to four weeks on smooth plastic surfaces.
The new coronavirus can apparently survive up to 28 days and remain infectious on glass or stainless steel, but also on smooth plastic surfaces. Scientists from the Australian Center for Disease Preparedness just featured this in the “Virology Journal.” The study contradicts all previous studies on the survival of Sars-CoV-2 on smooth surfaces. So far it has been said that the pathogen lasts a maximum of five days, but only a few infectious materials are present after hours.
Temperature and humidity are crucial
In the Australian laboratory, the viruses survived depending on the ambient temperature. At 20 degrees and 50 percent relative humidity, the particles lasted for almost a month, at 30 degrees for up to seven days. At 40 degrees, however, they only lasted a few hours on surfaces. Infectious coronaviruses generally survived slightly less on cotton: up to 14 days at 20 degrees or 3 days at 30 degrees.
For their experiments, the researchers poured a solution with infectious Sars-CoV-2 onto glass, stainless steel, vinyl, banknotes or cotton cloth. They allowed the samples to dry for an hour and then kept them under constant conditions for different periods of time. At defined times, the scientists washed individual pieces of the sprayed material and tested whether the cells could be infected with the solution. According to the researchers, the amount of virus in the initial solution corresponded to that emitted by a highly infectious person.
The laboratory study also corresponds to the real world to the extent that one can imagine an infected person coughing or sneezing into a touch screen, banknote, ATM keypad, or tram rail. Biological material then dries and can stick for a long time without deep cleaning of the surface. However, unlike the real world, the laboratory study samples were kept in complete darkness. We know that ultraviolet light breaks down coronaviruses.
Small significant smear infections
Virologist Eike Steinmann from the Ruhr University in Bochum, whose team has already conducted survival studies with Sars-CoV-2, believes that the Australian analysis was successful. But there is no reason to panic about the results. First, the survival times of the determined virus are unusually long. And secondly, the transmission of Sars-CoV-2 from a contaminated surface to a person has never been detected in everyday life. In contrast to transmission via virus-containing droplets and aerosols, according to all prior knowledge, such smear infections did not play a significant role in the current pandemic, Steinmann emphasizes. In the best-case scenario, in hospitals with highly contagious Covid-19 patients, contaminated surfaces could be a source of infection.
For a smear infection to occur, the person who has germs attached to their hands after touching a surface has to somehow get them to their nose, mouth, or eyes. This can happen, for example, if the person eats something with their fingers, picks their nose, or rubs their eyes. Unlike a cough, which one can barely defend against, a smear infection can be prevented with good hand hygiene.
