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What do we know about claims that masks do not work?

This article was published on
January 28, 2021

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Despite ongoing claims that masks do not work, research shows that masks do work to help prevent transmission of respiratory diseases like COVID-19 and influenza (flu). A recent lab study conducted by the U.S. Centers for Disease Control and Prevention found that by wearing two masks, people's protection against virus in the air (also called aerosolized particles) was dramatically increased. The study demonstrated that wearing any kind of mask provides significantly more protection against infectious aerosols than not wearing a mask. Additionally, when dummies who wore two masks - like cloth face masks over surgical masks - were exposed to infectious aerosols, their level of protection was roughly 92%. (The group now recommends fitting a cloth mask over a medical procedure mask, and knotting the ear loops of a medical procedure mask and then tucking in and flattening the extra material close to the face. However, the U.S. CDC does not recommend wearing two disposable masks at one time or another mask on top of a KN95 or N95 mask.) Research before the COVID-19 pandemic had already shown the effectiveness of masks in healthcare settings, in homes of infected people, as well as in public settings during previous outbreaks of diseases like severe acute respiratory syndrome (SARS). Research during the COVID-19 pandemic has provided more evidence that masks are effective for reducing community transmission and saving lives. Many governments that responded effectively to the COVID-19 pandemic and lost fewer lives as a result, such as Taiwan, have used policies that include wearing masks in public settings. Beyond health research on the benefits of wearing masks for reducing transmission and saving lives, economic research has also shown links between wearing masks and improved long-term business/economic outcomes. For example, research by Goldman Sachs suggests that adopting a national mask mandate requiring the public to wear masks in the U.S. could potentially reduce the need for renewed lockdowns that "would otherwise subtract nearly 5% from GDP (Gross Domestic Product)." As there are many different types of masks in the market, it is important to remember that masks can differ in effectiveness. For example, now that healthcare workers have a better supply of personal protective equipment (PPE) such as medical-grade N95 respirators and surgical masks, some public health professionals are now calling for the general public to also wear more effective medical-grade masks. Previous recommendations focused on fabric face coverings for the general public, in order to ensure supply of medical-grade masks for healthcare workers. Now that the supply chain has improved in response to the COVID-19 pandemic, community transmission may be reduced further by encouraging the public to switch to more effective medical-grade masks when possible. Some European countries have moved to require medical-grade masks in public settings. Similarly, some public health professionals suggest that the public can increase the effectiveness of fabric face coverings by wearing multiple layers to filter out more respiratory particles. Dr. Anthony Fauci, a leading doctor and scientist for the U.S. COVID-19 response, has encouraged doubling up masks to increase the protection offered by porous fabric face coverings. In summary, masks do work and this is supported by research, although different types of masks vary in their effectiveness and masks alone are insufficient to respond to the COVID-19 pandemic (other public health measures, like maintaining physical distance and hygiene, are also needed). Experts suggest now focusing on how to make wearing masks in public even more effective.

Despite ongoing claims that masks do not work, research shows that masks do work to help prevent transmission of respiratory diseases like COVID-19 and influenza (flu). A recent lab study conducted by the U.S. Centers for Disease Control and Prevention found that by wearing two masks, people's protection against virus in the air (also called aerosolized particles) was dramatically increased. The study demonstrated that wearing any kind of mask provides significantly more protection against infectious aerosols than not wearing a mask. Additionally, when dummies who wore two masks - like cloth face masks over surgical masks - were exposed to infectious aerosols, their level of protection was roughly 92%. (The group now recommends fitting a cloth mask over a medical procedure mask, and knotting the ear loops of a medical procedure mask and then tucking in and flattening the extra material close to the face. However, the U.S. CDC does not recommend wearing two disposable masks at one time or another mask on top of a KN95 or N95 mask.) Research before the COVID-19 pandemic had already shown the effectiveness of masks in healthcare settings, in homes of infected people, as well as in public settings during previous outbreaks of diseases like severe acute respiratory syndrome (SARS). Research during the COVID-19 pandemic has provided more evidence that masks are effective for reducing community transmission and saving lives. Many governments that responded effectively to the COVID-19 pandemic and lost fewer lives as a result, such as Taiwan, have used policies that include wearing masks in public settings. Beyond health research on the benefits of wearing masks for reducing transmission and saving lives, economic research has also shown links between wearing masks and improved long-term business/economic outcomes. For example, research by Goldman Sachs suggests that adopting a national mask mandate requiring the public to wear masks in the U.S. could potentially reduce the need for renewed lockdowns that "would otherwise subtract nearly 5% from GDP (Gross Domestic Product)." As there are many different types of masks in the market, it is important to remember that masks can differ in effectiveness. For example, now that healthcare workers have a better supply of personal protective equipment (PPE) such as medical-grade N95 respirators and surgical masks, some public health professionals are now calling for the general public to also wear more effective medical-grade masks. Previous recommendations focused on fabric face coverings for the general public, in order to ensure supply of medical-grade masks for healthcare workers. Now that the supply chain has improved in response to the COVID-19 pandemic, community transmission may be reduced further by encouraging the public to switch to more effective medical-grade masks when possible. Some European countries have moved to require medical-grade masks in public settings. Similarly, some public health professionals suggest that the public can increase the effectiveness of fabric face coverings by wearing multiple layers to filter out more respiratory particles. Dr. Anthony Fauci, a leading doctor and scientist for the U.S. COVID-19 response, has encouraged doubling up masks to increase the protection offered by porous fabric face coverings. In summary, masks do work and this is supported by research, although different types of masks vary in their effectiveness and masks alone are insufficient to respond to the COVID-19 pandemic (other public health measures, like maintaining physical distance and hygiene, are also needed). Experts suggest now focusing on how to make wearing masks in public even more effective.

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What our experts say

Despite ongoing claims that masks do not work, research shows that masks do work to help prevent transmission of respiratory diseases like COVID-19 and influenza (flu). A recent lab study conducted by the U.S. Centers for Disease Control and Prevention found that by wearing two masks, people's protection against virus in the air (also called aerosolized particles) was dramatically increased. The study demonstrated that wearing any kind of mask provides significantly more protection against infectious aerosols than not wearing a mask. Additionally, when dummies who wore two masks - like cloth face masks over surgical masks - were exposed to infectious aerosols, their level of protection was roughly 92%. (The group now recommends fitting a cloth mask over a medical procedure mask, and knotting the ear loops of a medical procedure mask and then tucking in and flattening the extra material close to the face. However, the U.S. CDC does not recommend wearing two disposable masks at one time or another mask on top of a KN95 or N95 mask.)

Research before the COVID-19 pandemic had already shown the effectiveness of masks in healthcare settings, in homes of infected people, as well as in public settings during previous outbreaks of diseases like severe acute respiratory syndrome (SARS). Research during the COVID-19 pandemic has provided more evidence that masks are effective for reducing community transmission and saving lives. Many governments that responded effectively to the COVID-19 pandemic and lost fewer lives as a result, such as Taiwan, have used policies that include wearing masks in public settings.

Beyond health research on the benefits of wearing masks for reducing transmission and saving lives, economic research has also shown links between wearing masks and improved long-term business/economic outcomes. For example, research by Goldman Sachs suggests that adopting a national mask mandate requiring the public to wear masks in the U.S. could potentially reduce the need for renewed lockdowns that "would otherwise subtract nearly 5% from GDP (Gross Domestic Product)."

As there are many different types of masks in the market, it is important to remember that masks can differ in effectiveness. For example, now that healthcare workers have a better supply of personal protective equipment (PPE) such as medical-grade N95 respirators and surgical masks, some public health professionals are now calling for the general public to also wear more effective medical-grade masks. Previous recommendations focused on fabric face coverings for the general public, in order to ensure supply of medical-grade masks for healthcare workers. Now that the supply chain has improved in response to the COVID-19 pandemic, community transmission may be reduced further by encouraging the public to switch to more effective medical-grade masks when possible. Some European countries have moved to require medical-grade masks in public settings.

Similarly, some public health professionals suggest that the public can increase the effectiveness of fabric face coverings by wearing multiple layers to filter out more respiratory particles. Dr. Anthony Fauci, a leading doctor and scientist for the U.S. COVID-19 response, has encouraged doubling up masks to increase the protection offered by porous fabric face coverings.

In summary, masks do work and this is supported by research, although different types of masks vary in their effectiveness and masks alone are insufficient to respond to the COVID-19 pandemic (other public health measures, like maintaining physical distance and hygiene, are also needed). Experts suggest now focusing on how to make wearing masks in public even more effective.

Context and background

False claims that masks do not work have been perpetuated by coronavirus skeptics and their followers. These claims often are not based in any research, reference research incorrectly, or cherry-pick data to suit the arguments. Some claims are started and spread by people who lack or misunderstand current information, while other claims are organized efforts to mislead others, often motivated by politics or profit-driven incentives. These false claims are concerning because they put lives at risk, prompting major organizations such as the United Nations to issue warnings about COVID-19 misinformation and disinformation.

A former New York Times reporter and spy novel writer named Alex Berenson is behind some of the false claims about masks, which have been circulating on conservative media and among conspiracy theorists. An unreviewed, self-published book by Berenson on COVID-19 was released in June 2020, which was banned from being sold on the Amazon Kindle platform over concerns about spreading misinformation. Elon Musk, an American businessman who has faced widespread criticism for spreading misinformation during the pandemic, publicly defended Berenson and Amazon eventually reversed the ban, sparking debate.

Previous books by Berenson on topics unrelated to the pandemic have also come under fire for spreading misinformation. For example, over 100 scientists and doctors wrote an open letter refuting inaccurate and harmful claims made by one of Berenson's books in 2019, pointing out many issues with the so-called scientific claims of the author (including selection bias, cherry picking data, and attributing cause to mere associations).

Resources

  1. Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis (Oxford Academic Clinical Infectious Diseases)
  2. Face Mask Use and Control of Respiratory Virus Transmission in Households (U.S. CDC)
  3. Use of disposable face masks for public health protection against SARS (BMJ Journal of Epidemiology and Community Health)
  4. Masks and medical care: Two keys to Taiwan's success in preventing COVID-19 spread (Elsevier Travel Medicine and Infectious Disease)
  5. Scientific Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2 (U.S. CDC)
  6. An evidence review of face masks against COVID-19 (Proceedings of the National Academy of Sciences of the U.S.)
  7. Face Masks and GDP (Goldman Sachs Research)Why Aren’t We Wearing Better Masks? (The Atlantic)
  8. Some European Countries Move To Require Medical-Grade Masks In Public (NPR)
  9. Double masking for COVID-19: Why Fauci recommends wearing two masks at once (CNET)
  10. Still Confused About Masks? Here’s the Science Behind How Face Masks Prevent Coronavirus (University of California San Francisco)
  11. A Thorough Debunking of COVID-19 Contrarianism (Current Affairs)
  12. Types, sources, and claims of COVID-19 misinformation (Reuters)
  13. During this coronavirus pandemic, ‘fake news’ is putting lives at risk (UNESCO)
  14. Elon Musk calls for Amazon breakup after Covid-19 skeptic claims it censored his book (CNBC)
  15. Here Are the Questions the Right's Favorite Coronavirus Truther Isn't Willing to Answer:
  16. Alex Berenson prefers not to be fact-checked (Vice)
  17. 100 Scholars and Clinicians Refute Inaccurate Claims in New Book (Drug Policy Alliance)
  18. Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021 (U.S. CDC)

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