Nearly a year after scientists showed that the coronavirus can be inhaled into small droplets called aerosols that remain indoors in the stagnant air, more than a dozen experts are asking the Biden administration to take immediate steps to limit airborne transmission of the virus high-risk environments such as meat packing plants and prisons.
The 13 experts – including several who assisted President Biden during the transition – urged the government to demand a combination of masks and environmental measures, such as better ventilation, to mitigate risks in various workplaces.
On Friday, the Centers for Disease Control and Prevention released new guidelines for reopening schools, but quickly ignored improved ventilation as a precaution. It was only in July that the World Health Organization recognized that the virus could remain in the air in crowded enclosed spaces, after 239 experts publicly asked the organization to do so.
In a letter to the government, the scientists detailed the evidence supporting the airborne transmission of the virus. It has become even more urgent for the administration to act now, experts said, because of the slow release of the vaccine, the threat of more contagious variants of the virus already circulating in the United States and the high rate of Covid-19 infections and deaths, despite the recent drop in cases.
“It’s time to stop the fact that the virus is transmitted mainly through the air,” said Linsey Marr, aerosol specialist at Virginia Tech.
“If we properly recognize this and put the right recommendations and guidelines into practice, this is our chance to end the pandemic in the next six months,” she added. “If we don’t do that, it may well drag on.”
The letter was delivered on Monday to Jeffrey D. Zients, coordinator of the Covid-19 response from the Biden government; Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention; and Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases.
The letter urged the CDC to recommend the use of high-quality masks, such as N95 respirators, to protect workers at high risk of infection. Currently, healthcare professionals rely primarily on surgical masks, which are not as effective against aerosol transmission of the virus.
Many workers vulnerable to infection are people of color, who have suffered the impact of the epidemic in the United States, experts noted.
Mr. Biden instructed the Occupational Safety and Health Administration, which sets out workplace requirements, to issue temporary emergency standards for Covid-19, including those related to ventilation and masks, by 15 March.
But OSHA will only require standards that are supported by CDC guidance, said David Michaels, an epidemiologist at George Washington University and one of the signatories.
(Dr. Michaels led OSHA during the Obama administration; the agency has not had a permanent leader since he left.)
“Until the CDC makes some changes, OSHA will have a hard time changing the recommendations it presents, because there is an understanding that the government should be consistent,” said Dr. Michaels. “And the CDC has always been seen as the leading agency for infectious diseases.”
Public health agencies, including the WHO, have been slow to recognize the importance of aerosols in the spread of the coronavirus. It was only in October that the CDC recognized that the virus can sometimes be transmitted over the air, after an intriguing sequence of events in which a description of how the virus spreads appeared on the agency’s website, disappeared and resurfaced two weeks later.
But the agency’s recommendations for accommodation at the workplace did not reflect this change.
At the beginning of the pandemic, the CDC said health professionals did not need N95 respirators and could even use bandanas to protect themselves. It also did not recommend facial coverage for the rest of the population.
The agency has since revised those recommendations. He recently recommended that people wear two masks or improve the fit of their surgical masks to protect themselves from the virus.
“But they don’t talk about why you need a better fitted mask,” said Dr. Donald Milton, an aerosol expert at the University of Maryland. “They are recognizing the importance of breathing and the route of transmission, but they are not saying this clearly on their various web pages.”
The agency recommends surgical masks for healthcare professionals and says that N95 respirators are only needed during medical procedures that generate aerosols, such as certain types of surgery.
But many studies have shown that healthcare professionals who do not have direct contact with Covid-19 patients are also at high risk of infection and should use high quality respirators, said Dr. Céline Gounder, an infectious disease specialist at Bellevue Hospital Center in New York and a consultant to Mr. Biden during the transition.
“The CDC has not emphasized the risk of aerosol transmission enough,” said Dr. Gounder. “Unfortunately, concerns about supply continue to cloud the discussion.”
Many hospitals still expect their staff to reuse N95 masks in accordance with the agency’s recommendation to reuse when supplies are low. But since the masks are no longer in short supply, the agency must change its recommendations, said Gounder.
“We really need to stop this N95 reuse and decontamination approach,” she added. “We’ve been at this for a year, and that really isn’t acceptable.”
Hospitals, at least, tend to have good ventilation so health workers are protected in other ways, experts said. But in refrigerators, prisons, buses or grocery stores, where workers are exposed to the virus for long periods, the CDC does not recommend high-quality respirators, nor does it endorse improvements in ventilation.
“If you go to other workplaces, this idea that aerosol transmission is important is virtually unknown,” said Michaels. In food processing plants, for example, a refrigerated environment and a lack of fresh air are the ideal conditions for the virus to develop. But the industry has not taken security measures to minimize the risk, he added.
Instead, employers follow the CDC’s recommendations for physical distance and surface cleaning.
The recent emergence of more contagious variants makes it urgent for the CDC to address airborne virus transmission, said Dr. Marr of Virginia Tech. Germany, Austria and France now require N95 respirators or other high-quality masks in public transport and stores.
Dr. Marr was one of the experts who wrote to WHO last summer to push for recognition of airborne transmission. She didn’t expect to be in a similar position again so many months later, she said, “It looks like Groundhog Day.”