When the coronavirus started spreading 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 advised that if anyone touched any of these contaminated surfaces – and then their eyes, nose, or mouth – they could become infected.
Americans responded in kind: They wiped groceries, quarantined mail, and cleared drugstore shelves with Clorox wipes. Facebook closed two of its offices for a & # 39; thorough cleaning & # 39 ;. The Metropolitan Transportation Authority in New York began disinfecting subways every night.
But the era of "hygiene theaterMay have come to an unofficial end this week when the C.D.C. has his guidelines for surface cleaning and noted that the risk of contracting the virus was from touching an infected surface less than 1 in 10,000
"Humans can be affected by the virus that causes Covid-19 through contact with contaminated surfaces and objects," said Dr. Rochelle Walensky, the director of the C.D.C., at a White House briefing on Monday. "However, there is some evidence that the risk of transmission through this route of infection is actually low."
Admission had to take a long time, say scientists.
"Finally," said Linsey Marr, an expert on airborne viruses at Virginia Tech. "We've known this for a long time and yet people are still so focused on cleaning surfaces." She added, "There really is no evidence anyone ever gotten Covid-19 from touching an infected surface."
During the early days of the pandemic, many experts believed that the virus spread mainly through large respiratory droplets. These droplets are too heavy to travel long distances through the air, but can fall on objects and surfaces.
In this context, a focus on scrubbing every surface seemed to make sense. "Surface cleaning is more familiar," said Dr. Marr. “We know how to do it. You can see people doing it, you can see the clean surface. And so I think it makes people feel safer. "
But in the past year it has become increasingly clear that the virus is spreading mainly by air – in both large and small droplets, which can stay in the air longer – and that sanding door handles and seats in the subway does little to keep people safe.
"The scientific basis for all these concerns about surfaces is very small – thin to none," said Emanuel Goldman, a microbiologist at Rutgers University, who wrote last summer that the risk of transmission to the surface was exaggerated. “This is a virus that you get by breathing. It is not a virus that you get by touching. "
The C.D.C. has previously recognized that surfaces are not the main way the virus spreads. But the agency's statements this week continued.
"The most important part of this update is that they are clearly communicating the correct, low risk of surfaces to the public, which is not a message that has been clearly communicated in the past year," said Joseph Allen, a construction safety expert. at Harvard TH Chan School of Public Health.
It remains theoretically possible to catch the virus from surfaces, he noted. But it takes a lot of things to go wrong: a lot of fresh, contagious virus particles have to be deposited on a surface, and then a relatively large amount has to be quickly transferred to someone's hand and then to their face. "Presence on a surface is not the same as risk," said Dr. Allen.
In most cases, cleaning with simple soap and water – in addition to washing your hands and wearing a mask – is enough to keep the likelihood of surface transfer low, according to the C.D.C.'s updated cleaning guidelines. In most mundane scenarios and environments, people don't need to use chemical disinfectants, the agency notes.
"What this does very helpful, I think, is telling us what not to do," said Donald Milton, an aerosol scientist at the University of Maryland. "A lot of spraying and atomizing chemicals does not help."
Still, the guidelines suggest that if someone with Covid-19 has been in a particular room for the past day, the area should be both cleaned and disinfected.
"Disinfection is only recommended in indoor settings – schools and homes – where there has been a suspected or confirmed case of Covid-19 in the past 24 hours," said Dr. Walensky at the White House briefing. "Also, in most cases, misting, disinfection and spraying over large areas or electrostatic is not recommended as the primary disinfection method and there are several safety concerns to consider."
And the new cleaning guidelines do not apply to healthcare facilities, which may require more intensive cleaning and disinfection.
Saskia Popescu, an infectious disease epidemiologist at George Mason University, said she was pleased with the new guideline, which "reflects our evolving data on transmission during the pandemic."
But she noted that it remains important to clean regularly – and wash good hands – to reduce the risk of catching not only the coronavirus, but other pathogens that can linger on a particular surface.
Dr. Allen said the school and business officials he spoke to this week expressed relief at the updated guidelines, which will allow them to withdraw some of their intensive cleaning regimes. "This frees up many organizations to spend that money better," he said.
Schools, businesses and other institutions that want to keep people safe should shift their focus from surfaces to air quality, he said, investing in improved ventilation and filtration.
"This should be the end of a deep cleanse," said Dr. Allen, pointing out that the misplaced focus on surfaces came at a real cost. “It has led to closed playgrounds, it has led to nets being pulled from basketball courts, it has led to the quarantine of books in the library. It has led to completely missed school days for thorough cleaning. It made me unable to share a pencil. So that's all that hygiene theater, and it's a direct result of not correctly classifying surface transmission as low risk. "
Roni Caryn Rabin contributed reporting