When the coronavirus began to spread in the United States last spring, many experts warned of the danger posed by surfaces. Researchers reported that the virus could survive for days on plastic or stainless steel, and the Centers for Disease Control and Prevention said if someone touched any of these contaminated surfaces – then touched their eyes , his nose or his mouth – he could be infected.
Americans have responded in kind, wiping down groceries, quarantining mail and clearing drugstore shelves of Clorox wipes. Facebook has closed two of its offices for a “deep clean”. New York’s Metropolitan Transportation Authority has started disinfecting subway cars every night.
But the era of the “hygiene theater” may have unofficially ended this week, when the CDC updated its surface cleaning guidelines and noted the risk of contracting the virus from touching a contaminated surface. was less than 1 in 10,000.
“People can be affected by the virus that causes Covid-19 through contact with contaminated surfaces and objects,” CDC director Dr. Rochelle Walensky said in a White House briefing Monday. “However, there is evidence that the risk of transmission by this route of infection is actually low.”
Admission is long overdue, scientists say.
“Finally,” said Linsey Marr, an airborne virus expert at Virginia Tech. “We’ve known this for a long time and yet people are still focusing so much on cleaning surfaces.” She added: “There is really no evidence that anyone has ever caught Covid-19 from touching a contaminated surface.”
At the start of the pandemic, many experts believed the virus was spread primarily through large respiratory droplets. These droplets are too heavy to travel long distances in air, but can fall on objects and surfaces.
In this context, focusing on cleaning all surfaces seemed logical. “Surface cleaning is more familiar,” Dr. Marr said. “We know how to do it. You can see the people doing it, you see the clean surface. And so I think it makes people feel more secure.
But over the past year, it has become increasingly clear that the virus mainly spreads through the air – both in large and small droplets, which can stay in the air longer – and that scouring door handles and subway seats do little to keep people safe.
“The scientific basis for all of this concern about surfaces is very thin – thin or none,” said Emanuel Goldman, a microbiologist at Rutgers University, who wrote last summer that the risk of surface transmission had been exaggerated. “It’s a virus that you catch when you breathe in. It is not a virus that you get from touching. “
The CDC has previously recognized that surfaces are not the primary means of spreading the virus. But the agency’s statements this week went further.
“The most important part of this update is that they clearly communicate to the public the correct and low risk of surfaces, which is not a message that has been clearly communicated over the past year,” said Joseph Allen, a building security expert. at Harvard TH Chan School of Public Health.
Catching the virus from surfaces remains theoretically possible, he noted. But it takes a lot to go wrong: a lot of fresh, infectious virus particles to lay on a surface, then for a relatively large amount of it to quickly transfer to someone’s hand, then onto their face. . “Presence on a surface does not equate to risk,” Dr. Allen said.
In most cases, cleaning with simple soap and water – in addition to washing hands and wearing a mask – is sufficient to keep the risk of surface transmission low, according to the cleaning guidelines. CDC day. In most everyday scenarios and environments, people don’t need to use chemical disinfectants, the agency notes.
“What it does very usefully, I think, is tell us what we don’t need to do,” said Donald Milton, an aerosol scientist at the University of Maryland. “Doing a lot of spraying and misting chemicals isn’t helpful.”
Still, the guidelines suggest that if a person with Covid-19 has been in a particular space in the last day, the area should be both cleaned and disinfected.
“Disinfection is only recommended in indoor environments – schools and homes – where there has been a suspected or confirmed case of Covid-19 within the last 24 hours,” Dr Walensky said during the House briefing White. “In addition, in most cases fogging, fumigation and electrostatic spraying over a large area is not recommended as the primary method of disinfection and carries several safety risks to consider.”
And the new cleaning guidelines do not apply to healthcare facilities, which may require more intensive cleaning and disinfection.
Saskia Popescu, infectious disease epidemiologist at George Mason University, said she was happy to see the new guidelines, which “reflect the evolution of our transmission data throughout the pandemic.”
But she noted that it remains important to continue to do regular cleaning – and maintain good hand washing practices – to reduce the risk of contracting not only the coronavirus, but any other pathogens that may linger on a surface. particular.
Dr Allen said school and business officials he spoke to this week expressed relief at the updated guidelines, which will allow them to opt out of some of their heavy-duty cleansing regimes. “It allows a lot of organizations to spend that money better,” he said.
Schools, businesses and other institutions that want to keep people safe should focus on air quality, he said, and invest in improved ventilation and filtration.
“This should be the end of deep cleaning,” Dr Allen said, noting that the misplaced focus on surfaces has had real costs. “It led to closed playgrounds, it led to the net being removed from the basketball courts, it led to the quarantine of books in the library. This led to missed school days for a deep clean. This led to not being able to share a pencil. So that’s all this hygiene theater, and it’s a direct result of not properly classifying surface transmission as low risk.
Roni Caryn Rabin report creation