CDC acknowledges aerosols as ‘main way’ of coronavirus spread
Droplets and airborne particles can travel distances beyond six feet, it says
In a major development, the Atlanta-based Centers for Disease Control and Prevention (CDC) has revised its guidelines to acknowledge that the “main way” the novel coronavirus (SARS-CoV-2) spreads is through droplets and aerosols.
The updated guidance on September 18 says that the virus most commonly spreads through “respiratory droplets or small particles, such as those in aerosols, produced when an infected person coughs, sneezes, sings, talks, or breathes”.
The CDC elaborates saying that these “particles can be inhaled into the nose, mouth, airways, and lungs and cause infection. This is thought to be the main way the virus spreads”.
Explaining the mechanism of virus spread, the revised guidelines reiterate that the virus may “spread through the droplets and airborne particles” that are formed when an infected person coughs, sneezes, sings, talks or breathes.
It also says that there is growing evidence that droplets and airborne particles can “remain suspended in the air” and be inhaled by others. Most importantly, it clearly states that droplets and airborne particles can “travel distances beyond six feet (for example, during choir practice, in restaurants, or in fitness classes)”.
In cautions that, in general, the risk of virus spread increases in indoor settings without good ventilation. The risk of spread increases when an infected person interacts more closely with others and the duration of such interaction is longer.
The last time the CDC revised its guidelines on virus spread was on July 16. Then, the CDC did not mention aerosols or airborne particles or about the likelihood of spread when a person breathes. It had only mentioned that the virus spreads from one person to another through respiratory droplets produced when an infected person coughs, sneezes or talks.
The World Health Organization on July 9 acknowledged that novel coronavirus can be airborne in closed settings and spread from one person to another.
Now that both the WHO and CDC have acknowledged airborne spread of the virus and that the virus can spread to distances greater than six feet in certain settings, it is important to adopt universal masking, especially in enclosed places with poor ventilation, and maintain physical distancing.