Masks gain strength as the most effective means against coronavirus in an increasingly rare scientific climate

"Wearing face masks in public is the most effective means of preventing human [coronavirus] transmission. Along with social distancing, quarantine, and contact tracing, [face masks] are the most likely way to stop the pandemic. of the COVID-19 ". With these resounding conclusions, a study was published yesterday in the prestigious PNAS magazine in which the Mexican Nobel Prize winner Mario J. Molina and his team affirmed that "air transmission was the dominant contagion route" in the case of SARS-CoV- two.

If confirmed, it would not only be a very important discovery. It would volatilize all the arguments against the masks and would expose what would be the biggest mistake of what is already the most important health crisis of the 21st century: ignoring the importance of the air transmission route in the expansion of the coronavirus. Are there really arguments to think that this is so? The truth is that no. At least with this job in hand.

However, this does not mean that the pro-mask theses are losing weight. Little by little, more studies are appearing in favor of the use of masks and intellectuals like Nassim Taleb begin to suggest that not only is it necessary to use it, but that it is more than enough to stop the epidemic. This is what we know so far

The strange PNAS study

Molina et al. 2020

The conclusions of the study that was published yesterday are devastating. Molina's team has analyzed three different scenarios (Wuhan, Italy and New York City) to try to understand if the evolution of the pandemic has any clear relationship with the measures that were taken. In light of their data, the researchers consider that the mitigation measures are not effective and that only the masks have a direct relationship with the slowing down of the infected curve.

However, there are some things that stand out and make it wise to take your conclusions carefully. The first is the simplicity of the model. In practice, the work tries to understand the evolution of infections in the different countries only taking into account the approved mitigation measures. Even assuming that masks play a very important role in this, it seems risky not to consider the other factors that act on the epidemic much more seriously.

The North American case is a good example: they assume that the only substantial difference between the response of New York City and that of the rest of the United States was the masks. Something that in light of the enormous differences that existed in the application of the recommendations for social distance, quarantine and isolation, these attributions seem that they would require a greater development than the completely obvious work (despite the emphatic nature of their conclusions).

There is also an understandable issue: the publishing path. Despite having had time, the study has not undergone a standard "peer review". This is what is known in the world as "communicated": authors can choose two experts to do the review instead of undergoing a double-blind process. As a curiosity, neither of the two experts that the authors have selected are epidemiologists (one is a computational chemist and the other is an expert in machine learning).

The "air route" is still controversial, but the masks win whole

Claudio Schwarz

As we have been explaining in recent days, the current consensus is that (although the virus can be transmitted via aerosols) the dominant route is transmission by respiratory flow droplets. The difference is brutal: if Molina and his team were right, the distance measurements without a mask would be insufficient. For now, however, what is insufficient is your data. In view of this work, it seems unlikely that this consensus will move in one direction or the other.

This does not mean that the use of the masks does not gain weight as the days go by. To habitual defenders like Nassib Taleb, who continues to work on his models to defend that only with the use of two masks we could control the epidemic, until new investigations that explain the positive impact it has had in regions like Germany , where they estimate a drop of between 2.3% and 13% in the first 10 days after the implementation of the mandatory mask or its central role in controlling the dreaded second wave.

In other words, while the weight of the SARS-CoV-2 air transmission remains 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. And furthermore, be that as it may, all the investigations that are underway are excellent news because they come to fill an inexplicable gap in the scientific evidence that we have needed to fill for years.

Image | Brian Mcgowan

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