Coronavirus COVID-19: An Evidence Based Scientific Analysis of Why Masks are Ineffective, Unnecessary, and Harmful

Nov 24, 2020

The Evidence AGAINST Masks

Big Data Analysis of 25 U.S. States and 23 Countries Concludes, “Neither Lockdowns nor Mask Mandates Lead to Reduced COVID Transmission Rates or Deaths

A new National Bureau of Economic Research (NBER) working paper by Andrew Atkeson, Karen Kopecky, and Tao Zha focused on countries and U.S. states with more than 1,000 COVID deaths as of late July. This analysis is the largest and most comprehensive analysis of the largest datasets to date. In all, the study included 25 U.S. states and 23 countries.

The paper’s conclusion is that the data trends indicate that nonpharmaceutical interventions (NPIs) – such as lockdowns, closures, travel restrictions, stay-home orders, event bans, quarantines, curfews, and mask mandates – do not seem to affect virus transmission rates overall.

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.

Systemic Reviews and Meta-Analysis of Multiple Randomized Controlled Trials Concludes that Face Masks Fail to Prevent Transmission of Viral Respiratory Pathogens

One of the largest and highest level of evidence studies on the effectiveness of face masks on the transmission of respiratory viruses, which was recently released by the CDC, is Jingyi Xiao, et al., Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings— Personal Protective and Environmental Measures, Emerging Infectious Diseases, Vol. 26, No. 5, (May 2020).

This CDC meta-analysis found that face masks failed to provide a significant reduction to virus transmission.

“In our systematic review, we identified 10 [Randomly Controlled Trials] that reported estimates of the effectiveness of face masks in reducing laboratory-confirmed influenza virus infections in the community from literature published during 1946–July 27, 2018. In pooled analysis, we found no significant reduction in influenza transmission with the use of face masks.”

There is limited evidence for their effectiveness in preventing influenza virus transmission either when worn by the infected person for source control or when worn by uninfected persons to reduce exposure.

Our systematic review found no significant effect of face masks on transmission of laboratory-confirmed influenza.

Mandates for children to wear face masks fails even a rational basis test, and is clearly not in a child’s best interest, when assessed through a factual, evidence-based analysis, rather than a fear-based lens. It is simply not rational to believe that face masks will be properly and studiously worn by young children for up to ten hours in a school day.

In fact, the overwhelming weight of scientific literature to date establishes that face masks do not prevent the spread of COVID-19 by, to, or from, children.

  • Radonovich, L.J. et al., N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial, JAMA. 2019; 322(9): 824–833. doi:10.1001/jama.2019.11645, 2019.

    “Among 2862 randomized participants, 2371 completed the study and accounted for 5180 HCW-seasons. … Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.”

  • Long, Y. et al., Effectiveness of N95 respirators versus surgical masks against influenza: A systematic review and meta‐analysis, J Evid Based Med. 2020; 1‐ 9.
    • A total of six [Randomized Controlled Trials] involving 9171 participants were included.
    • There were no statistically significant differences in preventing laboratory‐confirmed influenza, laboratory‐confirmed respiratory viral infections, laboratory‐confirmed respiratory infection and influenza-like illness using N95 respirators and surgical masks.
    • Meta‐analysis indicated a protective effect of N95 respirators against laboratory‐confirmed bacterial colonization.
    • The use of N95 respirators compared with surgical masks is not associated with a lower risk of laboratory‐confirmed influenza.
  • See e.g., Patrick Saunders-Hastings, et, al., Effectiveness of personal protective measures in reducing pandemic influenza transmission: A systematic review and meta-analysis, Epidemics, v. 20 (September 2017)
  • An April 2020 review by the Norwich School of Medicine found that “the evidence is not sufficiently strong to support widespread use of face masks”, but supports the use of masks by “particularly vulnerable individuals when in transient higher risk situations.”
  • Dr. Russell Blaylock, a nationally recognized board-certified neurosurgeon, health practitioner, author, and lecturer warns that not only do face masks fail to protect the healthy from getting sick, but they also create serious health risks to the wearer.

    [Recent studies] found that about a third of the [healthcare] workers developed headaches with use of the mask, most had preexisting headaches that were worsened by the mask wearing, and 60% required pain medications for relief. As to the cause of the headaches, while straps and pressure from the mask could be causative, the bulk of the evidence points toward hypoxia and/or hypercapnia as the cause. That is, a reduction in blood oxygenation (hypoxia) or an elevation in blood C02 (hypercapnia).

    It is known that the N95 mask, if worn for hours, can reduce blood oxygenation as much as 20%, which can lead to a loss of consciousness.

    The importance of these findings is that a drop in oxygen levels (hypoxia) is associated with an impairment in immunity. Studies have shown that hypoxia can inhibit the type of main immune cells used to fight viral infections called the CD4+ T-lymphocyte.

    This occurs because the hypoxia increases the level of a compound called hypoxia inducible factor-1 (HIF-1), which inhibits T-lymphocytes and stimulates a powerful immune inhibitor cell called the Tregs.

    This sets the stage for contracting any infection, including COVID-19 and making the consequences of that infection much graver. In essence, your mask may very well put you at an increased risk of infections and if so, having a much worse outcome.

  • See also Denis G. Rancourt, PhD, Masks Don’t Work: A review of science relevant to COVID-19 social policy, Ontario Civil Liberties Association, April 11, 2020.

    There have been extensive randomized controlled trial (RCT) studies, and meta-analysis reviews of RCT studies, which all show that masks and respirators do not work to prevent respiratory influenza-like illnesses, or respiratory illnesses believed to be transmitted by droplets and aerosol particles.

    Furthermore, the relevant known physics and biology, which I review, are such that masks and respirators should not work. It would be a paradox if masks and respirators worked, given what we know about viral respiratory diseases: The main transmission path is long residence-time aerosol particles (< 2.5 µm), which are too fine to be blocked, and the minimum-infective-dose is smaller than one aerosol particle.

  • Jacobs, J. L. et al. (2009) Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: A randomized controlled trial, American Journal of Infection Control, Volume 37, Issue 5, 417 – 419

    “N95-masked health-care workers (HCW) were significantly more likely to experience headaches.”

    “Face mask use in HCW was not demonstrated to provide benefit in terms of cold symptoms or getting colds.”

  • Cowling, B. et al., Face masks to prevent transmission of influenza virus: A systematic review, Epidemiology and Infection, 138(4), 449-456. doi:10.1017/S0950268809991658 2010. prevent-transmission-of-influenza-virus-a-systematic

    “None of the studies reviewed showed a benefit from wearing a mask, in either [Health Care Workers] or community members in households…”

  • bin-Reza et al., The use of masks and respirators to prevent transmission of influenza: a systematic review of the scientific evidence, Influenza and Other Respiratory Viruses 6(4), 257–267, 2012.

    “There were 17 eligible studies. … None of the studies established a conclusive relationship between mask ⁄ respirator use and protection against influenza infection.”

  • Offeddu, V. et al., Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis, Clinical Infectious Diseases, Volume 65, Issue 11, 1 December 2017, Pages 1934–1942.

    “Self-reported assessment of clinical outcomes was prone to bias. Evidence of a protective effect of masks or respirators against verified respiratory infection (VRI) was not statistically significant.”

In fact, many physicians and researchers now believe that, because the ineffectiveness of face masks in stemming the spread of Covid-19 is so widely known and acknowledged in the scientific and medical communities, the goal of widespread mask mandates is based entirely on low-level observational studies, speculative mechanistic studies, fear, and politics, not science.

  • See Michael Klompas, M.D., M.P.H., et. al., Universal Masking in Hospitals in the Covid-19 Era, New England Journal of Medicine, N Engl J Med 2020; 382:e63 (May 21, 2020).

    “We know that wearing a mask outside health care facilities offers little, if any, protection from infection. . . It is also clear that masks serve symbolic roles. Masks are not only tools, they are also talismans that may help increase health care workers’ perceived sense of safety, well being, and trust in their hospitals. Although such reactions may not be strictly logical, we are all subject to fear and anxiety, especially during times of crisis. One might argue that fear and anxiety are better countered with data and education than with a marginally beneficial mask.”

  • Lisa M Brosseau, ScD, Margaret Sietsema, PhD, COMMENTARY: Masks-for-all for COVID-19 not based on sound data, Center for Infectious Disease Research and Policy, University of Minnesota, April 1, 2020. based-sound-dataDr. Brosseau is a national expert on respiratory protection and infectious diseases and professor (retired), University of Illinois at Chicago. Dr. Sietsema is also an expert on respiratory protection and an assistant professor at the University of Illinois at Chicago. They made the following key points in their commentary:

    “We do not recommend requiring the general public who do not have symptoms of COVID-19-like illness to routinely wear cloth or surgical masks because:

    There is no scientific evidence they are effective in reducing the risk of SARS-CoV-2 transmission.

    Their use may result in those wearing the masks to relax other distancing efforts because they have a sense of protection.

    We need to preserve the supply of surgical masks for at-risk healthcare workers.”

In an August 2020 article, Denis G. Rancourt, PhD, a Researcher, Ontario Civil Liberties Association, debunks supposed “studies” purporting to support compelled face mask use for the general population.

  • See Rancourt, Face masks, lies, damn lies, and public health officials: “A growing body of evidence” August 2020. lthofficialsAgrowingbodyofevidence

    “[T]here is no policy-grade evidence to support forced masking on the general population, . . . all the latest-decade’s policy-grade evidence points to the opposite: NOT recommending forced masking of the general population.”);

    No [randomized controlled trial] study with verified outcome shows a benefit for [health-care workers] or community members in households to wearing a mask or respirator. There is no such study. There are no exceptions. Likewise, no study exists that shows a benefit from a broad policy to wear masks in public (more on this below).

    Furthermore, if there were any benefit to wearing a mask, because of the blocking power against droplets and aerosol particles, then there should be more benefit from wearing a respirator (N95) compared to a surgical mask, yet several large meta-analyses, and all the RCT, prove that there is no such relative benefit.

    Masks and respirators do not work. (emphasis added);

  • Denis G. Rancourt, PhD, Masks Don’t Work: A Review of Science Relevant to COVID-19 Social Policy, River Cities Reader, June 11, 2020. covide-19-social-policy
  • see also, Todd McGreevy, Still No Conclusive Evidence Justifying Mandatory Masks, River Cities Reader, August 12, 2020.

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.

A July 2020 review by the University of Oxford, Centre for Evidence-Based Medicine found that there is no evidence that cloth masks are at all effective against virus infection or transmission.

A July 2020 study by Japanese researchers found that cloth masks “offer zero protection against coronavirus.”


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.

Duke Scientists reveal that cloth masks increase aerosolization of viral particles

Duke scientists tested a variety of masks and found that cloth masks, “…seemed to disperse the largest droplets into a multitude of smaller droplets (see fig. S5), which explains the apparent increase in droplet count relative to no mask in that case. Considering that smaller particles are airborne longer than large droplets (larger droplets sink faster), the use of such a mask might be counterproductive.”[1]

Neck fleeces, also called gaiter masks and often used by runners, were the least effective. In fact, wearing a fleece mask resulted in a higher number of respiratory droplets because the material seemed to break down large respiratory droplets into small droplet nuclei that aerosalize, remain suspended in the air for hours, and are capable of traveling large distances with movements of the air.

Folded bandanas and knitted masks also performed poorly and did not offer much protection.

We were extremely surprised to find that the number of particles measured with the fleece actually exceeded the number of particles measured without wearing any mask,’ Fischer said.[2]

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