« Wearing face masks in public is the most effective way to prevent transmission [del coronavirus] between humans. In addition to social isolation, quarantine and contact tracing, [las mascarillas] they are the most likely way to stop the COVID-19 pandemic. “With these resounding findings, a study was published yesterday in the prestigious PNAS magazine in which Mexican Nobel laureate Mario J. Molina and his team said” airborne transmission was the primary means of contagion “in the case of SARS-CoV- 2.
If confirmed, it wouldn’t just be a very important finding. This would volatilize all arguments against masks and expose what would be the biggest mistake of what is already the biggest health crisis of the 21st century: ignoring the importance of the air route in the expansion of the coronavirus. Are there really any arguments for thinking that this is so? The truth is no. At least with this job in hand.
however, does not mean pro-mask theses lose weight. Gradually, more and more studies are emerging in favor of the use of masks and intellectuals like Nassim Taleb are starting to suggest that not only is their use necessary, but that it is enough to stop the epidemic. This is what we know so far
The strange PNAS study
Molina et al. 2020
Study results released yesterday are devastating. Molina’s team analyzed three different scenarios (Wuhan, Italy and New York) to try to understand if the evolution of the pandemic has a clear relationship with the measures that have been taken. In light of their data, the researchers consider that mitigation measures are not effective and that only masks have a direct relationship with slowing the infected curve.
However, there are some things that grab attention and make be careful to draw conclusions carefully. The first is the simplicity of the model. In practice, the work tries to understand the evolution of infections in different countries by taking into account only approved mitigation measures. Even assuming that masks play a very important role in this regard, it seems risky not to take the other factors influencing the epidemic more seriously.
The North American case is a good example: They assume that the only substantial difference between New York’s response and that of the rest of the United States were the masks. In light of the huge differences in the application of recommendations regarding social distancing, quarantine and isolation, these attributes seem would require more development than work quite obvious (despite the emphatic nature of his conclusions).
There is also an understandable problem: the post path. Although it had time, the study was not subject to a standard “peer review”.. This is known worldwide as a “press release”: authors can choose two experts to do the review instead of going through a double-blind process. Out of curiosity, neither of the two experts selected by the authors is an epidemiologist (one is a computer scientist and the other is an expert in machine learning).
Air route remains controversial, but masks win it all
As we have explained in recent days, the current consensus is that (although the virus can be transmitted via aerosols) the dominant route is transmission through respiratory flow droplets. The difference is brutal: if Molina and her team were right, distance measurements without a mask would be insufficient. For now, however, what is not enough is your data. In view of this work, it seems unlikely that this consensus will evolve one way or the other.
This does not mean that the use of masks does not gain weight over the days. To usual defenders like Nassib Taleb, who continues to work on his models to defend that only the use of two masks would allow us to control the epidemic, until new investigations which explain the positive impact it has had in regions like Germany
where they feel a decrease of between 2.3% and 13% in the first 10 days after putting on the compulsory mask or its central role in controlling the dreaded Second Wave.
In other words, although the weight of SARS-CoV-2 airborne transmission is still open, the truth is that the mask appears as an almost essential measure to begin to regain social and economic life with a minimum of guarantees and security. Plus, anyway, all of the ongoing investigations are great news because they fill an inexplicable gap in scientific evidence that we have had to fill for years.
Image | Brian Mcgowan