The US Centre for Disease Control and Prevention (CDC) on Friday updated its guidance to confirm that the coronavirus also spreads through so-called “aerosol transmission”. This effectively means the pathogen transmits and proliferates through not just close contact but also by inhalation of very fine particle mist exhaled by an infected person which can remain suspended in the air.
The agency now states explicitly that airborne virus can be inhaled even when one is more than six feet away from an infected individual. Although such transmission has long been factored in by many researchers and public health officials, the updated guideline is a change from the agency’s previous position that most infections were through close contact and surface transmissions.
Although the guidance maintains that “the principal mode by which people are infected is through exposure to respiratory fluids carrying infectious virus”, it says the virus can also be transmitted in poorly ventilated and/or crowded indoor settings, because “aerosols remain suspended in the air or travel farther than 1 metre”. Some experts had worried that the CDC had underplayed such airborne aerosol transmission, which would make not just social distancing but even personal distancing imperative. The guidance endorses the advice that masking and distancing, not to speak of ventilation, is important even in closed family situations.
Although the fine differentiation between aerosol/fine mist and droplets might seem like pettifogging to some, experts said it could still lead to important guidelines. For instance, it may be better to be outdoors, with social distancing, than be indoors, even with family members, in poorly-ventilated spaces. The new guidelines put a question mark on the three-feet distancing in classrooms that schools in US have used to reopen, suggesting it may need to be revised.