The Science Behind Using a Mask - COVID-19 Clinical Trial
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The Science Behind Using a Mask

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    One year ago, face masks didn’t hold a place in the consciousness of the American public. Aside from standard use by healthcare workers, masks simply didn’t matter in our day to day lives.  

    Well, what a difference a few months make. Masks are now the focus of entire newscasts, scientific studies, CDC briefings, and presidential statements. Hollywood celebrities are using their social media platforms to encourage mask wearing while restaurants and grocery stores are turning away customers who refuse to don a face covering. 

    Thanks to these efforts, it’s generally understood that masks prevent the spread of COVID-19 and protect vulnerable individuals, but what’s the science behind the mask? 

    Who Do Masks Protect? 

    As explained by CDC Director Dr. Robert R. Redfield, “We are not defenseless against COVID-19. Cloth face coverings are one of the most powerful weapons we have to slow and stop the spread of the virus – particularly when used universally within a community setting.” 

    In their simplest forms, masks prevent the person wearing the mask from spreading COVID-19 to others. They also offer the secondary benefit of shielding others from respiratory droplets traveling through the air. 

    “I think the biggest thing with COVID now that shapes all of this guidance on masks is that we can’t tell who’s infected,” said infectious disease specialist Peter Chin-Hong, MD. “You can’t look in a crowd and say, oh, that person should wear a mask. There’s a lot of asymptomatic infection, so everybody has to wear a mask.” 

    What Does the Evidence Show? 

    The true efficiency of masks has only been studied for a few months, but scientists already have established a growing body of evidence that suggests face masks are worth wearing. 

    In one laboratory study of respiratory droplets, researchers captured and studied high-speed video to determine that hundreds of droplets running from 20 to 500 micrometers are generated when speaking a simple phrase. More importantly, nearly all of those droplets are blocked when the mouth is covered. 

    Some experts believe the epidemiologic data speaks even louder than the laboratory studies. In a hair salon in Missouri, for example, nearly 140 people interacted with two hair stylists with confirmed cases of coronavirus. However, not a single customer ended up showing symptoms of COVID-19, and masks are credited for stopping the spread. 

    Both stylists experienced symptoms in mid-May but continued working for a week after falling ill. At the time, the area had such a low rate of COVID-19 cases that both stylists assumed their symptoms were related to allergies. In the days after receiving positive test results for coronavirus, the two stylists entered isolation while health officials contact-traced all 139 people exposed to the stylists and asked them to self-quarantine for two weeks. Not a single customer reported feeling sick during those 14 days. Of the 67% of those customers who accepted the offer of a free COVID-19 test, all turned up negative. 

    Interviews with 104 of the 139 customers revealed that the stylists and customers all wore face coverings or masks at all times during the appointments. Researchers believe this made the difference and ultimately stopped transmission. 

    “Had they not been using those masks, we would have expected a totally different situation,” said Dr. Juan Gutierrez, a biologist studying coronavirus transmission. 


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