The CDC has confirmed that COVID-19 can be spread through airborne transmission, officially acknowledging which situations are more high-risk during the pandemic. Until now, the US Centers for Disease Control and Prevention had been cautious about confirming fears that even six feet of distance between people may be insufficient to stop the transmission of coronavirus, and that in some settings infectious particles can linger for hours.
Now, in an update to the CDC site today, new guidelines make that risk abundantly clear. While “COVID-19 most commonly spreads during close contact,” the CDC said, it “can sometimes be spread by airborne transmission.”
Those at highest risk are still people who get within 6 feet of a person with coronavirus, or who have direct contact with them. When infected people “cough, sneeze, sing, talk, or breathe they produce respiratory droplets,” the CDC explains. These can vary in size from visible through to smaller droplets, and cause infection when inhaled or deposited on membranes such as those inside the nose and mouth.
However the CDC also acknowledges that airborne transmission is a key as well. “Some infections can be spread by exposure to virus in small droplets and particles that can linger in the air for minutes to hours,” the agency explains. “These viruses may be able to infect people who are further than 6 feet away from the person who is infected or after that person has left the space.”
That’s much the same as how other infections such as tuberculosis, measles, and chicken pox are spread.
“There is evidence that under certain conditions, people with COVID-19 seem to have infected others who were more than 6 feet away,” the CDC says. “These transmissions occurred within enclosed spaces that had inadequate ventilation. Sometimes the infected person was breathing heavily, for example while singing or exercising.”
“Under these circumstances, scientists believe that the amount of infectious smaller droplet and particles produced by the people with COVID-19 became concentrated enough to spread the virus to other people,” the CDC concludes. “The people who were infected were in the same space during the same time or shortly after the person with COVID-19 had left.”
The recommendations remain a focus on social distancing, of at least 6 feet apart whenever possible, and to cover the nose and mouth with a mask. Washing hands regularly, and sanitizing surfaces are also essential. The CDC also says to avoid spending time in “crowded indoor spaces” too, as well as to ventilate indoor spaces with as much outdoor air as possible so as to reduce the potential for lingering respiratory droplets that are infectious.
Update: In a new statement, the CDC, acknowledged that the guidance has evolved, but insists that its overall recommendations remain the same:
“CDC continues to believe, based on current science, that people are more likely to become infected the longer and closer they are to a person with COVID-19. Today’s update acknowledges the existence of some published reports showing limited, uncommon circumstances where people with COVID-19 infected others who were more than 6 feet away or shortly after the COVID-19-positive person left an area. In these instances, transmission occurred in poorly ventilated and enclosed spaces that often involved activities that caused heavier breathing, like singing or exercise. Such environments and activities may contribute to the buildup of virus-carrying particles” CDC