Is coronavirus also transmitted via aerosol? In the US comes first confirmation and then denial

According to the US CDC, the virus is also transmitted through aerosols, it was read on their official page. But the update was then promptly removed: it was an un-revised draft and published by mistake. How much do we actually know?

(image: Getty Images) Is coronavirus also transmitted by traveling through the air or only by close contact with infected people? The US CDCs (Centers for Disease Prevention and Control) on Friday 18 September published an update in the guidelines on the subject, explaining that airborne (or aerosol) transmission is one of the possible routes of contagion. This brief addition on the Cdc page, however, was only noticed on Sunday 20 September by the CNN, which promptly gave the news. But the CDC then quickly removed the update on Monday 21st, explaining that they are still working on revising the guidelines on the issue and that a premature draft had been published by mistake. Here's how it went.

Transmission via aerosol: the update of the Cdc

On the page of the Cdc on the transmission routes of Sars-Cov-2 on Friday 18 September we read that the “ Covid-19 is mainly transmitted between people in close contact with one another "and that the virus spreads" through respiratory droplets (droplets) or small particles, such as those in aerosols, produced when an infected person coughs, sneezes, sings, speak or breathe ". In short, even through an aerosol of very small particles, that is, smaller than 5 micrometers (thousandths of a millimeter) present in the air - but it is not yet known how long they would remain suspended and active once in the air.



These particles, it was always read in the Cdc update reported by CNN and now removed, can cause infection when inhaled through the "nose, mouth, respiratory tract and lungs. It is believed that [through droplets and aerosols, ed] is the main route of transmission of the virus ". And again: "there is growing evidence that droplets and airborne particles can remain suspended in the air and breathed in by other people, and that they can travel beyond 6 feet [about 1 meter and 80, ed] for example, when sings in a choir, restaurant or gym […] In general, the risk is higher in indoor environments that do not have good ventilation ”. The recommended distance from the CDs is therefore at least 1.8 meters.

Cdc: the update was canceled

But shortly after the CDs promptly cancel what was written, talking about a publication error on the web page. "Unfortunately a very early version of the review was published without a technical review," Jay Butler, deputy director of the CDC dealing with infectious diseases, said in an article in The Washington Post. And currently on the dedicated page we read that "a version of the draft with the changes proposed for these new recommendations was published by mistake on the official website of the Agency. The CDCs are currently updating recommendations regarding the airborne transmission of SARS-Cov-2. Once this process is complete the change will be published. "

It would be a central change

It was a" defining change "- as he always stated in The Washington Post, before removal of the update, Jose-Luis Jimenez, professor of chemistry at the University of Colorado in Boulder, who studies the aerosol transmission of viruses - an important addition to knowing the transmission routes of the virus and taking increasingly adequate measures to counter it. Not all infections and infectious diseases are also transmitted via airborne (some only by direct person-to-person contact). Among those that also count an aerosol infection there is for example measles, very contagious.

What we know about airborne transmission

The theme of the airborne transmission of Sars-Cov-2 is been repeatedly taken up by scientists and beyond. To date, there is no clear and unambiguous answer on the possibility that the coronavirus will remain in the air, spread and become infected. So far, according to the World Health Organization (WHO) and other health authorities, according to previous evidence, airborne transmission is not one of the main routes of contagion, even if a large group of scientists disagree and wrote to WHO asking to review this position. In short, the doubts are many. Several researches have shown that outdoor, outdoors, concentrations of viral rna are very low and even if the topic is still to be explored to date "it is unlikely that this transmission route is the basis of a significant outdoor contagion mechanism. ”, As recently explained Daniele Contini, researcher at the CNR Institute of Atmospheric and Climate Sciences, not involved in the survey, who has been dealing with the topic for some time. Different, according to the expert, is the case of indoor airborne transmission, where this contagion would be more likely.

In short, there are still no certainties, even if the experts of the national and international authorities are working to accumulate evidence and provide some more knowledge.