When the first cases of Covid-19 began to appear in Australia, some people reported disinfecting their groceries before taking them home, and there were also concerns that the virus might be living on the surfaces of packages sent by mail. During Victoria’s prolonged blockade, teams of workers could be seen walking the city streets, disinfecting traffic lights, benches and even fences.
An epidemiologist at La Trobe University, Associate Professor Hassan Vally, said that just over a year later it became clear that superficial transmission is not as significant a factor in the spread of Covid-19 as was feared. Although surface transmission is not impossible, Vally said his role in the spread needs perspective.
“I want to make it clear that nothing should change in terms of hand washing and personal hygiene,” said Vally. “We can, however, be less anxious to wash all surfaces 20 times a day, and just focus on good hand hygiene and social distance, and stay at home when we are sick, which should be more than enough to prevent us from spreading the virus. ”
The spread of aerosol by close contact is the determining factor in the transmission of Covid-19, especially when an infected person is in close contact with another person and transmits small liquid particles [droplets and aerosols] containing the virus, especially when they cough and sneeze. These aerosols enter the nose, mouth and eyes of those close to you.
In an article for the Conversation, Vally said: “This does not mean that surface transmission is not possible and that it does not represent a risk in certain situations, or that we should completely disregard it. However, we must recognize that the representations of threats on the transmission surface are relatively small ”.
Emanuel Goldman, professor of microbiology at Rutgers University in the United States, wrote in the medical journal Lancet that studies that warned of surface transmission were conducted in the laboratory and “bear little resemblance to real-life scenarios.”
“In my opinion, the chance of transmission through inanimate surfaces is very small, and only in cases where an infected person coughs or sneezes on the surface and another person touches that surface shortly after coughing or sneezing (within 1–2 hours) ), ”Said Goldman.
“I don’t disagree with being over-cautious, but that can go to extremes not justified by the data.” Periodic disinfection of surfaces and the use of gloves can be reasonable precautions in environments such as hospitals, he said, but it is probably overkill for less risky environments.
Feeding the concern about the spread of the surface seemed alarming, but exaggerated studies, including one by the Australian government agency CSIRO, which found that a drop of fluid containing the virus in concentrations similar to the levels seen in infected patients could survive on surfaces such as money and glass for up to 28 days.
What much of the news about the study failed to mention is that it was done in the dark to remove the effect of ultraviolet light, which helps to 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 experience different humidity and temperature throughout the system and will also be exposed to light, making the survival of the virus in the mail extremely unlikely.
Science was not wrong, Vally said, but the interpretation and explanation of the results was.
But aren’t many hygiene measures better than absolutely safe?
Vally said the problem was tiredness of compliance.
“A lot of psychological research says that we only have a certain amount of willpower and a certain amount of details on which we can focus our attention,” said Vally. “That’s why Apple founder Steve Jobs wore the same clothes every day, based on the idea that you can only make many decisions a day and exercise a certain amount of willpower.
“For me, as we learn more about the virus, we must be sure that we are not concerned with things that we should not be concerned with, we do not want to focus our attention on things that are out of proportion to the threat they pose. That way, we will have more energy to focus on the things that matter and that helps us save time and money too. “
Peter Collignon, an infectious disease doctor and professor at Australian National University, agrees that all the available evidence says it is the people nearby talking, coughing, singing and breathing heavily that drive the spread of the virus.
“They are inhaling and reaching the nose and the eyes, and that is the main risk factor,” he said. That’s why eye protection, especially in quarantined hotels and hospitals, should be prioritized as much as masks and social detachment, he said.
Collignon cites a large study published in the Journal of the American Medical Association that found that 19% of healthcare professionals were infected, despite wearing three-layer surgical masks, gloves and shoe protectors and using alcohol. After the introduction of face shields, no workers were infected.
“I think we underestimate the importance of the eyes and place too much emphasis on surfaces,” said Collignon.