Masks: Deja vu, All Over Again

November 29, 2021 Joe Brady

After almost two years of dealing with the COVID-19 Pandemic, it is unbelievable that we are still having discussions about basic, common-sense public health issues, like vaccines and wearing masks. By now most everyone has noticed that whenever public health officials remove the mask mandates, within a few weeks infections and hospitalizations go up, and whenever mask mandates are in place, the infections go down. Yet in spite of the mountain of scientific evidence available, we still see media and political pundits putting out misinformation and outright lies as to the effectiveness of public health measures. At this point in the pandemic, this is “weapons-grade stupidity”, which will cost lives. “Following the science” does not mean cherry-picking the studies and citing only those that agree with your preexisting political ideas from right-wing publications like “City Journal”. Following science means looking at all the data. This is the purpose of a review study. You must eliminate the articles that are merely someone’s opinion or that unfairly equate apples and oranges. You must look at the actual data, evaluate the quality of that data and look at how many other studies agree with the conclusions you are touting. This is the whole point of a “peer-reviewed scientific journal”. In January of 2021, The Proceedings of the National Academy of Sciences published just such a review of studies on the efficacy of mask-wearing in preventing the spread of COVID-19. 

Jeremy Howard, Austin Huang, Zhiyuan Li, Zeynep Tufekci, Vladimir Zdimal, Helene-Mari van der Westhuizen, Arne von Delft, Amy Price, Lex Fridman, Lei-Han Tang, Viola Tang, Gregory L. Watson, Christina E. Bax, Reshama Shaikh, Frederik Questier, Danny Hernandez, Larry F. Chu, Christina M. Ramirez, Anne W. Rimoin, Proceedings of the National Academy of Sciences Jan 2021, 118 (4) e2014564118; DOI: 10.1073/pnas.2014564118

The science around the use of masks by the public to impede COVID-19 transmission is advancing rapidly. The Proceedings review, recommends using an analytical framework to examine mask usage, synthesizing the relevant scientific literature to look at multiple variables such as population impact, transmission characteristics, source control, wearer protection, sociological considerations, and implementation considerations. 

A Cochrane review (15) on physical interventions to interrupt or reduce the spread of respiratory viruses included 67 RCTs and observational studies. It found that “overall masks were the best performing intervention across populations, settings, and threats.” This is not to say that hand washing, physical distancing, and vaccines are not important, on the contrary when you are in a fight for your life you do everything to help win. Defeating COVID is going to involve an all-out effort at disease prevention. 

The preponderance of evidence indicates that mask-wearing reduces transmissibility per contact by reducing the transmission of infected respiratory particles in both laboratory and clinical studies. 

Preventing the airborne transmission of disease was well known in Chinese medicine as early as the thirteenth century. Marco Polo noted in his diary the Chinese practice of wearing masks to prevent the spread of airborne diseases (this is anecdotal evidence). The first experimental data comes from Wu Lien Teh’s work to control the 1910 Manchurian Plague. Scientists today consider this “a milestone in the systematic practice of epidemiological principles in disease control”

L. G. Goh, T. Ho, K. H. Phua, Wisdom and western science: The work of Dr Wu Lien-Teh. Asia Pac. J. Publ. Health 1, 99–109 (1987).Google Scholar

L. T. Wu, A Treatise on Pneumonic Plague (League of Nations, Health Organization, 1926), pp. 373–398.Google Schola, 

In his research, Wu identified the cloth mask as “the principal means of personal protection.” Wu reported on experiments that showed a cotton mask was effective at stopping airborne transmission, as well as on observational evidence of efficacy for health care workers.

These are just a couple of studies so the review looked at all the carefully conducted studies since 1910 and included them in its analysis.

Based upon a review of 141 carefully controlled clinical and epidemiological studies (listed below) the Proceedings of the National Academy of Sciences strongly recommend that public officials and governments strongly encourage the use of widespread face masks in public, including the use of appropriate regulation.

Rather than paraphrase I will let readers review the conclusions of the review for yourselves and if you wish further information check out the references from which these conclusions are drawn.


Our review of the literature offers evidence in favor of widespread mask use as source control to reduce community transmission: Nonmedical masks use materials that obstruct particles of the necessary size; people are most infectious in the initial period postinfection, where it is common to have few or no symptoms (45, 46, 141); nonmedical masks have been effective in reducing transmission of respiratory viruses; and places and time periods where mask usage is required or widespread have shown substantially lower community transmission.

The available evidence suggests that near-universal adoption of nonmedical masks when out in public, in combination with complementary public health measures, could successfully reduce

ReRe to below 1, thereby reducing community spread if such measures are sustained. Economic analysis suggests that mask-wearing mandates could add 1 trillion dollars to the US GDP (32, 34).

Models suggest that public mask-wearing is most effective at reducing the spread of the virus when compliance is high (39). We recommend that mask use requirements are implemented by governments, or, when governments do not, by organizations that provide public-facing services. Such mandates must be accompanied by measures to ensure access to masks, possibly including distribution and rationing mechanisms so that they do not become discriminatory. Given the value of the source control principle, especially for presymptomatic people, it is not sufficient for only employees to wear masks; customers must wear masks as well.

It is also important for health authorities to provide clear guidelines for the production, use, and sanitization or reuse of face masks, and consider their distribution as shortages allow. Clear and implementable guidelines can help increase compliance, and bring communities closer to the goal of reducing and ultimately stopping the spread of COVID-19.

When used in conjunction with widespread testing, contact tracing, quarantining of anyone that may be infected, hand washing, and physical distancing, face masks are a valuable tool to reduce community transmission. All of these measures, through their effect on Re Re, have the potential to reduce the number of infections. As governments exit lockdowns, keeping transmissions low enough to preserve health care capacity will be critical.”

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