Masks in Reducing the Spread of Infectious Disease

An Evidence Based Scientific Analysis of Why Masks are Ineffective, Unnecessary, and Harmful

Jim Meehan

  • Decades of the highest-level scientific evidence (meta-analyses of multiple randomized controlled trials) overwhelmingly conclude that medical masks are ineffective at preventing the transmission of respiratory viruses, including SAR-CoV-2.
  • Those arguing for masks are relying on low-level evidence (observational retrospective trials and mechanistic theories), none of which are powered to counter the evidence, arguments, and risks of mask mandates.
  • The majority of the population is at very low to almost no risk of severe or lethal disease from CoVID-19. Children are at an extraordinarily low risk of dying from CoVID-19. Based on CDC published data, 99.99815% of children that contract CoVID-19 survive.
  • Transmission of SARS-CoV-2 among children in schools and daycares is very rare.
  • Masks worn properly are well documented to cause harm to their wearers. Masks worn improperly, re-used, or contaminated are dangerous.
  • Any reasonable risk to benefit analysis of medical masks concludes that the risks overwhelmingly outweigh the benefits.
  • Children are at imminent risk of harm from mask mandates.

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The Year of Disguises

Roger W. Koops

“One of the big mistakes by modelers is the concept of a face covering or mask as a “barrier.” I see many references to so-called “experts” who make this claim. This is completely false. No face covering or mask is a barrier. Either they do not know what they are talking about or they are misleading people.”

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COMMENTARY: Masks-for-all for COVID-19 not based on sound data

Lisa M Brosseau ScD; Margaret Sietsema, PhD

Sweeping mask recommendations—as many have proposed—will not reduce SARS-CoV-2 transmission, as evidenced by the widespread practice of wearing such masks in Hubei province, China, before and during its mass COVID-19 transmission experience earlier this year. Our review of relevant studies indicates that cloth masks will be ineffective at preventing SARS-CoV-2 transmission, whether worn as source control or as PPE. 

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The Science: Masks Are Neither Effective Nor Safe

This 2020 meta-analysis found that evidence from randomized controlled trials of face masks did not support a substantial effect on transmission of laboratory-confirmed influenza, either when worn by infected persons (source control) or by persons in the general community to reduce their susceptibility.

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No Evidence Facemasks Keep Kids & Teachers Safe

Carl Heneghan

“That’s all I ever do is say, where’s the evidence to inform what we do and if it’s lacking, you have to come down on the side of not intervening.

“Now one of the key problems we’ve got when we intervene, is it becomes incredibly difficult to roll back interventions. And that’s what we are saying. That’s the great problem now, the just in-case approach. That’s not how to perform in healthcare.”

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Masking: A Careful Review of the Evidence

Paul E. Alexander

“…it is not unreasonable at this time to conclude that surgical and cloth masks, used as they currently are, have absolutely no impact on controlling the transmission of Covid-19 virus, and current evidence implies that face masks can be actually harmful.”

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Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers

The recommendation to wear surgical masks to supplement other public health measures did not reduce the SARS-CoV-2 infection rate among wearers by more than 50% in a community with modest infection rates, some degree of social distancing, and uncommon general mask use. The data were compatible with lesser degrees of self-protection.

“However, WHO acknowledges that we lack evidence that wearing a mask protects healthy persons from SARS-CoV-2 (prevention).”

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A cluster randomised trial of cloth masks compared with medical masks in healthcare workers

C Raina MacIntyre; Holly Seale; Tham Chi Dung; Nguyen Tran Hien; Phan Thi Nga; Abrar Ahmad Chughtai;, Bayzidur Rahman; Dominic E Dwyer;, Quanyi Wang

This study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated.

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Surgical mask to prevent influenza transmission in households: a cluster randomized trial

Laetitia Canini; Laurent Andréoletti; Pascal Ferrari; Romina D'Angelo; Thierry Blanchon; Magali Lemaitre; Laurent Filleul; Jean-Pierre Ferry; Michel Desmaizieres; Serge Smadja; Alain-Jacques Valleron; Fabrice Carrat

In various sensitivity analyses, we did not identify any trend in the results suggesting effectiveness of facemasks.

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Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?

Anna Davies; Katy-Anne Thompson; Karthika Giri; Georged Kafatos; Jimmy Walker; Allan Bennett

Homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals.

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Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: a randomized controlled trial

Joshua L Jacobs; Sachiko Ohde; Osamu Takahashi; Yasuharu Tokuda; Fumio Omata; Tsuguya Fukui

Face mask use in health care workers has not been demonstrated to provide benefit in terms of cold symptoms or getting colds.

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Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis

Jeffrey D. Smith MSc; Colin C. MacDougall MSc; Jennie Johnstone MD PhD; Ray A. Copes MD; Brian Schwartz MD; Gary E. Garber MD

Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

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A replaceable, more efficient filter for N95 masks

American Chemical Society

N95 masks provide the “highest level of protection,” but this new filter has a smaller pore size, “potentially blocking more virus particles.”

[But…surgical masks work as well as N95 for influenza transmission.]

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