The federal health authorities updated the public guidelines on the spread of the coronavirus on Friday, emphasizing that the transmission occurs through inhalation of very fine respiratory droplets and aerosolized particles, as well as through contact with sprayed droplets or by touching contaminated hands with the mouth, nose or eyes.
The Centers for Disease Control and Prevention now explicitly state – in large, bold letters – that airborne viruses can be breathed even if you are more than three feet from an infected person. The new language, released online, is a change from the agency’s previous position that most infections were acquired through “close contact, not airborne transmission”.
As the pandemic played out last year, infectious disease experts warned for months that both the CDC and the World Health Organization were overlooking research that strongly suggested the coronavirus was floating in the air in small particles. Several scientists on Friday welcomed the agency’s abolition of the term “close contact”, which they criticized as vague and which did not necessarily capture the nuances of aerosol transfer.
“Now the CDC has caught up with the latest science, got rid of some old problematic terms and thought about how the transmission happens,” said Linsey Marr, aerosol expert at Virginia Tech.
The new focus underscores the need for the federal agency for occupational safety and health to issue standards for employers to address potential hazards in the workplace, some experts said.
“They hadn’t talked much about aerosols and focused more on droplets,” said David Michaels, an epidemiologist at the George Washington School of Public Health and head of OSHA in the Obama administration.
He and other researchers expressed concern that the CDC has not yet reaffirmed its recommendations on preventing exposure to aerosolized viruses.
The new information has a significant impact on the indoor climate and especially on the workplaces, said Dr. Michaels. Virus-laden particles “retain their properties in the air for hours and accumulate in a room that is not well ventilated.”
“There’s more exposure closer,” said Dr. Michaels. “But if you are further away there is still a risk, and those particles are still in the air.”
Donald Milton, an aerosol scientist at the University of Maryland, agreed that federal officials should come up with better guidelines for workplace safety.
“We need to better focus on good breathing apparatus for people who have to be around other people for long periods of time,” said Dr. Milton. “A surgical mask, even if it’s hidden around the edges, still doesn’t give you enough protection when you’re elbow-to-elbow with other people in a meat packing facility.”
Health care workers, bus drivers, and other workers may also need respirators, said Dr. Michaels. Customers in retail stores should continue to keep their distance and wear masks, he added. Good ventilation is of the utmost importance with these settings.
Dr. Marr pointed out that an updated page on the CDC website entitled “How Covid-19 Spreads” states that inhaling the virus when people are far apart is “unusual”. The statement is “misleading and potentially harmful,” said Dr. Marr.
“If you are in a poorly ventilated area, a virus will build up in the air and everyone in that room will be exposed.”