The US CDC recognizes for the first time that the coronavirus can be transmitted through the air: what it means and what implications it has for us
This weekend, the US Center for Disease Control and Prevention (CDC), the country’s highest epidemiological authority, just officially recognized that the coronavirus is airborne and can get transmitted through the air. The same indications state that “it is thought to be the main form of spread of the virus”; however, due to the language used, there is some debate among experts. Either way, it is the latest update on a long controversy among scientists, technicians and authorities around the world for exactly understanding the mechanisms that SARS-Cov-2 uses to spread.
The recognition by the CDC constitutes a whole accolade to those who defend the importance of aerosols (small particles that can be in the air longer than flow droplets) in the transmission of the virus. But what exactly does this decision mean and what implications does it have on our daily lives?
What exactly has the CDC said?
In its latest update, the CDC has significantly changed its explanation of how the virus is transmitted. Until September 18, they spoke about the direct contact and the droplets that we produce when we cough, sneeze or speak “as the main forms of diffusion.” However, its September 18 update says that the most common transmission routes are:
Through respiratory droplets or small particles, such as those in aerosols, produced when an infected person coughs, sneezes, sings, talks, or breathes:
- 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.
As supporters and detractors of aerosol theory recognize, the chosen language lends itself to confusion and, in fact, in recent hours we can find experts convinced that the main role of aerosols has been recognized and those who believe they have not. Although this recognition appears to be express at first reading, there are valid interpretative arguments on both sides of the debate.
HUGE DEVELOPMENT: CDC just accepted that the main way in which COVID-10 spreads is through aerosols!!
"aerosols […] produced when an infected person […] sings, talks, or breathes can be inhaled and cause infection.
**This is thought to be the main way the virus spreads** pic.twitter.com/qdpz5mb3Iu
— Jose-Luis Jimenez (@jljcolorado) September 20, 2020
46/ Existing guidance (some aerosol, not naming it) was not used E.g. we helped @WHO write ventilation guidance.
But made no difference. People reported: not taken seriously or implemented by any government, because after all, the virus was not in the airhttps://t.co/ApR24a45jk
— Jose-Luis Jimenez (@jljcolorado) September 21, 2020
The truth is that it is difficult to know if the CDC has carefully chosen the language used and will maintain it or whether it will be modified in the following updates it makes regularly. Until then, it would be adventurous to affirm one thing or the other. However, it is certainly that the Centers for Disease Control and Prevention already openly recognizes that the virus is airborne; something that, until now, it was reluctant to do or considered only a distant possibility.
What does this mean?
At the outset, the first implication is that it is gradually recognized that air transmission has a more important role than originally thought. During the first months of the pandemic, it was thought that (in addition to direct contact) there were two fundamental pathways by which the virus could spread: through contact with contaminated surfaces and through droplets of respiratory flow. A third way was under discussion: that the virus could be transmitted through air/aerosols (i.e. in small particles, without the need for drops).
However, as the knowledge we had on the matter has advanced, the recommendations of those same authorities have changed. In fact, progressively, they have been adapting to an “aerosol type” scenario rather than a “droplet type” to the point that, although the CDC has significantly changed the theoretical position, it has not moved a single comma from the practical recommendations. Substantially, the health recommendations are the same as we’ve been having.
So, how does this impact our day to day?
Indeed, there are not too many differences between the current recommendations and the recommendations of an aerosol scenario. This does not mean that it does not imply changes in the recommendations and measures that have been taken in countries. It involves, for example, a change in emphasis on outdoor activities, on the use of indoor masks (masks with the highest possible security) and on investing in ventilation and purification systems for the air (or directly leaving spaces that are impossible to ventilate properly).
Some of the experts who have most defended the importance of aerosols, often insists on the idea that in the face of an “aerosol scenario”, citizens should stop thinking about the virus as something that comes to us through coughing and sneezing and start thinking of it as smoke in a room. To think and act accordingly: airing rooms and using all the means at our disposal to purify the air we breathe.
In any case, it is important to bear in mind that it does not make much sense to wait for the WHO or any other institution to recognize certain things to adapt our behaviour to these types of scenarios. These types of measures do not pose any problem in a flow droplet scenario, so it is reasonable to try to minimize our exposure by adapting to the assumption that entails more risks.