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Study suggests mask-wearing reduces the odds of self-infection with SARS-CoV-2

Masks could stymie COVID-19 infection by impeding one’s own speech droplets from moving from the nose, mouth, or throat into the lungs. Image credit: Shutterstock/insta_photos

Masks could prevent the worst of COVID-19 infections by impeding one’s own virus-laden speech droplets from moving from the nose, mouth, or throat into the lungs. Image credit: Shutterstock/insta_photos

COVID-19 typically turns deadly when the virus infects the lungs. Hence, how exactly SARS-CoV-2 gets deep into the respiratory tract has been a pressing question since the pandemic started early last year. One pathway is well known: Most people catch the virus in their nose or mouth and then accidentally suck a droplet of their own saliva or nasal drip into their lungs, often while they are asleep. A recent research letter published in the Journal of Internal Medicine proposes a second possible pathway: self-infection to the lungs via one’s own speech.

The idea, says coauthor Adriaan Bax, a biophysicist at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at the NIH in Bethesda, MD, is that a cloud of infectious droplets spews into the air and hangs around a person’s face for minutes every time they speak. And through sheer chance, because speaking emits a lot of droplets, the possibility of breathing a droplet into the lungs essentially becomes “Russian roulette,” he says. Previous research in 2020 found that masks reduce severe disease, and this latest study suggests that the reason is a reduction in self-infection after initially catching the virus in the upper respiratory tract.

To begin to test this hypothesis, Bax turned to the Deaf community because it “spans the broadest possible spectrum of vocalization,” he explains, ranging from people who rely exclusively on American Sign Language to those who use a substantial amount of vocalized speech. Bax contacted coauthor Poorna Kushalnagar, who is deaf, in the autumn of 2020, wondering if there had been many studies on the extent to which deaf people who prefer not to speak were impacted by COVID-19. “There were none,” says Kushalnagar, a public health research scientist at Gallaudet University in Washington, DC, which specializes in educating deaf students. Intrigued, she agreed to help gather data using surveys of participants.

Kushalnagar designed surveys of 102 participants, all of whom had recovered from COVID-19, and all of whom were born deaf or lost their hearing early in life. Surveys included a number of questions to quantify the severity of each person’s COVID-19 symptoms, such as how much time they spent in bed and whether they were hospitalized, as well as how often each person spoke and if they wore a mask regularly.

Regression analysis of the survey responses confirmed that participants who spoke less also got less sick, as did those who regularly wore a mask. But both of those relationships were individually weak. It wasn’t until the coauthors combined the two factors in the regression that infrequent vocalization and regular mask wearing together showed a strong correlation with reduced disease severity. That these two factors can’t be uncoupled suggests that masks catch speech droplets, preventing self-infection deeper in the respiratory tract, Bax says.

A process called nucleated condensation may be one key to these results, Bax points out. The speech particle flies out of the mouth large and wet and into the hot, wet environment between one’s face and a mask. As the particle crosses the mask, the particle gets even larger because the atmosphere cools, but the absolute humidity stays the same. Large droplets are trapped in the cloth mask and so can’t be breathed back in.

While a “provocative” and “very creative” idea that intuitively makes sense, the behavior of these tiny airborne droplets, and how exactly they swell, shrink, are caught, or pass through a mask, needs further characterization, says Donald K. Milton, a physician and aerobiologist specializing in infectious airborne particles at the University of Maryland in College Park. Chris Cappa, an environmental engineer at the University of California (UC), Davis, agrees that it’s an interesting hypothesis but notes that rebreathing one’s own speech particles may sweep in a cloud of virus-laden droplets that just sweep right out again. Because of the physics of particle motion at such small sizes, some of the droplets may collide with a mucus surface and infect it, but some may not. “I’d like to see some of the more physics-based modeling,” Cappa says—this could help demonstrate, he adds, whether inhaling speech particles actually lets them get deeper in the lungs than they otherwise would.

William Ristenpart, a chemical engineer at UC Davis, questions some of the study’s assumptions, noting it’s “unclear why the authors assume that wearing a facemask will reduce inhalation of self-emitted expiratory particles.” Exhaling naturally pushes speech droplets away from the face, where they’re diluted in the air, he notes. A facemask would trap them and make them more likely to be inhaled on the next breath. What’s more, Ristenpart notes that while most people speak in conversation with a partner, this study didn’t control for the chance of lung infections by a partner’s speech droplets.

Bax disagrees, noting that speech droplets naturally hang around the face in a cloud initially less than 0.5 meters from the speaker’s mouth, and that masks easily trap and hold these droplets, which become glued to the microscopic threads of the cloth, so that the drops aren’t inhaled. He adds that the medical community widely accepts that COVID-19 tends to begin in the nose, mouth, or throat, and then migrates to the lungs and other organs. The odds of someone else’s speech droplet getting into one’s lungs are small. Self-exposure through one’s own speech is a lot more likely, Bax says, which is evinced by the correlation between less vocalization and less severe symptoms.

To date, about 56% of the US population has received at least one dose of a COVID-19 vaccine. Hence, many people have cast aside their masks. But if this hypothesis is correct, people who wear masks aren’t just protecting others, they’re protecting themselves as well, Cappa says. Even vaccinated people, Bax adds, could, in principle, benefit from wearing a mask in the immediate aftermath of a known exposure. Mask-wearing would reduce the odds that any virus loitering in the nose, mouth, or throat could spread into the lungs and cause even mild symptoms.

Bax now hopes to expand this study, which had a relatively small sample size. He’s aiming to go from about 100 participants to thousands. One avenue he’s exploring now is surveying monks at Buddhist Monasteries in India and Nepal, many of whom take a vow of silence.  “A survey of that population,” Bax says, “potentially could provide definitive answers on how effectively silence or mask wearing can prevent severe disease.”

Other recent papers recommended by Journal Club panelists:

Complete Degradation of a Conjugated Polymer into Green Upcycling Products by Sunlight in Air

Inhibitors of bacterial H2S biogenesis targeting antibiotic resistance and tolerance

Genome design of hybrid potato

Predicting population genetic change in an autocorrelated random environment: Insights from a large automated experiment

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4 Responses to Study suggests mask-wearing reduces the odds of self-infection with SARS-CoV-2

  1. M S says:

    To hypothesize is human, to prove through a peer-review gauntlet is divine.

    More to the point – we need more work on the benefits vs the cons of masking individuals over a protracted period of time. The cloth masks that were initially recommended to the public (so that there would not be a run on N95s) became the mainstay masking for so many people. Even after N95 shortages were alleviated, US health authorities continued to demonstrate cloth masks and surgical masks – both of which are not fitted masks – to the public. But are cloth masks effective enough, and how frequently do they need to be changed? I there a case for a different kind of “split” mask that routes away from the nose the plume of particles expelled from the mouth during speaking? Thanks.

  2. says:

    Well I am congenitally deaf since birth. Then the recent genetic testing results have: COX-26 as a recessive gene causing: Genetic Deafness in my D’Auria Family Tree on long lineage. I inform you that I have a rare blood type that is: O Negative and Rh Negative in a fact. Now I am fully vaccinated after I received a first dose of Plizer vaccine on March 25 2021, and a second dose of Plizer vaccine on April 15 2021. Recently I read the scientific reviews about the research studies of persons with O Negative and Rh Negative have very lower risks to contribute COVID-19, then they better react to COVID-19 vaccines. I am the well-educated Gallaudet University graduate with B.A. in majors of Biology and Chemistry from Gallaudet University with Class of 1981. Well I have heard that the updates about Delta and Lambyma variants are the most dangerous mutant varieties under COVID classifications in a fact. All of times I wear the masks then I practice in 6 feet distances, self-quarantine at home and other safety measures as I have followed CDC and NIH guidelines. I originally came my strong, well-educated & college-educated Italian-American Middle Class family with privileges who were strong in sciences, mathematics and health care fields. Greatly I have appreciated to Dr. Anonthy Facuci, the NIAD Director as the White House’s medical chief advisor to our US President Joe Biden at best recognition. Regards, Christa D’Auria

  3. Lou says:

    Very interesting study and more or less prove of self-infection with SARS-CoV-2 by breathing and speaking.

    Only problem is there is never ever delivered any prove of a Virus causing the existing of a Corona resp. of a SARS1, SARS2 or SARS-CoV-2d-Virus!
    There is delivered prove that the SARS-CoV-2d-Scamdemic is in reality a CIA-DARPA-5G-WiFi-AI-BioWarfare-pandemic using extreme toxic Graphene Oxide Nano-particles being extreme soluble and existing (intentionally brought in) in the water we drink and air we breathe with masses of cell-killing Nano-spikes passing any barrier to the brain/hearth/organs and massive loaded now by extreme toxic vaccines and tests.

    It is also proven that this 5G-operations were/are since WW2 forced and spread over the world and on humanity together with the Graphene Oxide science/technology/application in an extreme short period of time without any testing and regulations for their PetroPharma-Cartel, Food-Cartel, Energy-Cartel and Banking- and Regulations-Cartel all owned/controlled by less then 0.0001% of mankind being Jacques Attali-Kissinger-Gates-Schwab- Cousteau- Dr.Canderon-90% reduction-Banksters- types.
    As Attali, Dr. Canderian agree expliciet with their opinion “that 95% of the world’s population are “Useless Eaters” who need to be euthanized as quickly as possible”.
    So, we asked Mylo, “How can the “vaccinated” know with certainty how long they have to live once they have been jabbed?” He answered with the information, called the “End of Cycle Formula”.
    He explained how easy it is to calculate.
    “The Power of Simplicity” , he said. “There is a maximum cycle of ten years from injection to End of Cycle” [or death], he elaborated. “And it is extremely easy to determine”.
    He said any hematologist can see it within seconds under a microscope, and even more readily under an electron microscope. “The percentage of blood affected [or contaminated] by or with Graphene Oxide is the reciprocity of the End of Cycle calculation” , he divulged.
    In other words, an “inoculatee” [as he calls anyone jabbed with the Experimental Use Authorization Eugenics Depopulation Lethal Injection Bioweapon] “having 20% Graphene Oxide deterioration in their blood will, barring any other input criteria, live for 8 years. [10 years less 20%] ”.
    “Someone with 70% Graphene Oxide deterioration will not live more than 3 years. [10 years less 70%]”.
    Mylo further: “It is all measurable through hematological testing. The more shots and boosters the imbeciles get, the worse their blood will look under a microscope, and the quicker they will turn to fertilizer.” (see: )

    So, above article is absolutely correct when reading Graphene Oxide-droplets instead of not existing Virus-droplets.
    As a result Covid 19 , part of Agenda 21-30, will be Covid 21-30 realised with their 5G-EMF-WiFi-AI-Graphene Oxide-BioWarfare-pandemic-90%depopulation-program.

    To stay alive, take care for your Melatonine-, Glutathione-, Testosterone-, Zinc- and your Vitamin C, E, D3-levels being far more important than toxic masks, tests and vaccines loaded with toxic Graphene Oxide.

  4. Sandy says:

    This “hypothesis” is, as is a plethora of speculative rubbish in the last 16 months, absolutely ludicrous. Kovid has produced some of the most unscientific publishing in the history of the modern world. Hypothetical data projections are now studies? Variants are trumped as so deadly they require variant vaccines projected far into the future? Masks, distancing, tracking tracing, testing, quarantine and LOCKDOWN are a “new normal” as dictated by “experts” without full vetting in public with extensive debate, with all sidess included equally, with advice and voted consent?

    The PCR tests are now abandoned by the CDC because as even the inventor of the PCR test told us, it is not be used to find viral infection. I could go on for hours. You folks who work in this field, find a job where a corporation or business interest is NOT dictating your research, your focus, your funding and the workplace peer pressure that corrupts objectivity and the goal of providing for the social and health needs of humanity.

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