The United States’ Centers for Disease Control and Prevention (CDC), on Monday, revealed that COVID-19 can spread through virus lingering in the air, sometimes for hours, thereby reversing its earlier pronouncement and acknowledging concerns widely voiced by public health experts about the airborne transmission of the virus.
In the updated guidance, the CDC said that Covid-19 can sometimes be spread by airborne transmission. It said some infections can be spread by exposure to the virus in small droplets and particles, or aerosols, that can linger in the air for minutes to hours.
The CDC’s updated guidance comes weeks after the agency published, and then took down a similar warning, sparking debate over how the virus spreads.
In Monday’s guidance, CDC said there was evidence that people with COVID-19 possibly infected others who were more than 6 feet away, within enclosed spaces with poor ventilation.
Under such circumstances, CDC said scientists believe the amount of infectious smaller droplets and particles, or aerosols, produced by the people with COVID-19 become concentrated enough to spread the virus.
The CDC has long warned of transmission through small droplets that shoot through the air and generally fall to the ground, which resulted in the six-feet social distancing rule. Aerosol droplets are much smaller still and can remain suspended in the air, like smoke.
A group of US scientists had warned on Monday that aerosols lingering in the air could be a major source of COVID-19 transmission, although CDC stresses that close-contact transmission is more common than through air.
Some researchers in a press call said, “The reality is the airborne transmission is the main way that transmission happens at close range with prolonged contact.’’
The researchers disclosed that viruses in aerosols can remain in the air for seconds to hours, travel more than two meters and accumulate in poorly ventilated indoor air, leading to super spreading events.
Since individuals with COVID-19 release thousands of virus-laden aerosols and far fewer droplets while breathing and talking, the scientists said the focus must be on protecting against airborne transmission.
“The new guidance is also clear about asymptomatic transmission as it said that people who are infected but do not show symptoms can also spread the virus to others,” it says.
They also said that public health officials should clearly differentiate between droplets ejected by coughing or sneezing and aerosols that can carry the virus to greater distances.
Public health officials must highlight the importance of moving activities outdoors and improving indoor air, along with wearing a mask and social distancing, the letter said.
It can be recalled that many researchers and doctors have said for months that coronavirus can be transmitted through small airborne viral particles. In July, 239 scientists published a letter that urged the World Health Organization and other public health organizations to be more forthcoming about the likelihood that people could catch the virus from droplets floating in the air.