When Covid-19 cases began to emerge in Australia, some people reported sanitizing their groceries before bringing them home, and there were also concerns that the virus could be living on the surfaces of packages in the mail. During the prolonged closure of Victoria, teams of workers could be seen walking the streets of the city sanitizing buttons on traffic lights, benches and even fences.
An epidemiologist at the University of La Trobe, Associate Professor Hassan Vally, said that just over a year later it has become apparent that surface transmission is not as important a factor in the spread of Covid-19 as had been feared. While surface transmission is not impossible, Vally said its role in propagation needs perspective.
“I want to make it clear that nothing should change in terms of washing our hands and personal hygiene,” Vally said. “However, we can be less eager to wash all surfaces 20 times a day, and just focus on good hand hygiene and social distancing, and stay home when we’re sick, which should be more than enough to avoid that we spread the virus. “
The spread of the aerosol by close contact is the determining factor in the transmission of Covid-19, mainly when an infected person is in close contact with another person and transmits small liquid particles. [droplets and aerosols] that contain the virus, especially when they cough and sneeze. These sprays then enter the nose, mouth, and eyes of those nearby.
In an article for The Conversation, Vally said: “This is not to say that surface transmission is not possible and does not pose a risk in certain situations, or that we should ignore it entirely. But we must recognize that the threat posed by surface transmission is relatively small. “
Emanuel Goldman, a professor of microbiology at Rutgers University in the United States, wrote in the medical journal The Lancet that the studies warning about surface transmission have been conducted in the laboratory and “bear little resemblance to real-life scenarios.”
“In my opinion, the possibility of transmission through inanimate surfaces is very small, and only in cases where an infected person coughs or sneezes on the surface and someone else touches that surface shortly after coughing or sneezing (within 1 to 2 hours), ”Goldman said.
“I do not disagree with being cautious, but this can go to extremes that the data does not justify.” Periodic surface disinfection and the use of gloves may be reasonable precautions in settings such as hospitals, he said, but is probably overkill for less risky settings.
Fueling concerns about the spread on the surface were seemingly alarming but exaggerated studies, including one from the Australian government agency CSIRO that found that a drop of liquid containing the virus in concentrations similar to those seen in infected patients could survive on surfaces like money. cash and glass for more than 28 days.
What many of the news reports on the study did not mention was that it was carried out in the dark to eliminate the effect of ultraviolet light that helps kill viruses. Humidity and temperatures in the real world vary constantly, which is different from carefully controlled temperatures in a laboratory. Mail, for example, will go through different humidities and temperatures throughout the system and will also be exposed to light, making virus survival in mail extremely unlikely.
The science wasn’t bad, Vally said, but the interpretation and explanation of the results was.
But aren’t too many hygiene measures better to be absolutely sure?
Vally said the problem was compliance fatigue.
“There’s been a lot of psychological research that says we only have a certain amount of willpower and a certain amount of detail that we can focus our attention on,” Vally said. “This is why Apple founder Steve Jobs wore the same clothes every day, based on the idea that you can only make so many decisions a day and exert some willpower.
“For me, as we learn more about the virus, we should make sure that we are not concerned about things that should not concern us, we do not want to focus our attention on things that are disproportionate to the threat they pose. That way, we will have more energy to focus on the things that are important and that helps us save money and time as well.
Peter Collignon, an infectious disease physician and professor at the Australian National University, agreed that all the available evidence says that it is people who are in close proximity to each other, talking, coughing, singing and gasping for air that drives the spread of the virus.
“They breathe them in and it gets into their noses and eyes and that’s the main risk factor,” he said. That’s why eye protection, particularly in quarantined hotels and hospitals, should be given as much priority as masks and social distancing, he said.
Collignon cites a large study published in the Journal of the American Medical Association that found that 19% of healthcare workers became infected, despite wearing three-layer surgical masks, gloves and shoe covers and using an alcohol sanitizer. . After the introduction of face shields, no workers were infected.
“I think we have underestimated the importance of eyes and overpriced surfaces,” Collignon said.