Of masks and men: no clear evidence masks are effective in COVID-19

The question on whether to wear a mask or not during the COVID-19 pandemic in terms of effectiveness in stopping viral spread remains contentious and unresolved. On balance, the evidence is severely conflicted and leans toward masks having no significant effect in stopping spread of respiratory virus. This question is now overwrought with steep politicization. Arguments against the use of masks in the current COVID-19 pandemic emerged when a recent CDC case-control study (a weaker design due to an inability to control for all key confounding factors, though employing sub-optimal adjustment) reported that 84.4% of cases always or often wore masks. This raised many questions as to the utility of masks in the COVID-19 emergency.

Moreover, accumulating evidence in toto suggests a lack of evidence to support mask use (in adults or children) including as a broad mask mandate e.g. CDCOxford’s CEBMCIDRAP and policyKlompas and universal maskingJefferson et al., CDC 2, Brainard et al. (Norwich School of Medicine), and Hunter et al. My overall conclusion Based on the body of evidence, is that there is no conclusive evidence to support the use of masks for COVID-19 (except N-95 type masks in a hospital setting and when appropriately utilized) and in fact masking appears to carry substantial risks to the user. 

Urgent well-designed clinical research is needed to definitively address the question about the utility of face masks in curtailing or stopping spread of COVID-19. It is surprising that researchers have not commissioned adequate face mask studies or social distancing studies since the onset of COVID-19 in February 2020. This was not Herculean. We are way past the time in research whereby we can make illogical or irrational, often intellectually dishonest statements not backed with evidence and data. It appears that the face mask issue is now fraught with politics and agendas by medical experts and the media. The cognitive dissonance by experts must end as well as the politicization of this mask question. Populations are being hurt by the academic sloppiness and reckless behavior of these camera-hungry experts and ill-informed media. COVID-19 conclusions are often baseless and I suspect the research community has not studied the mask issue appropriately and have viewed it as Damoclean, because they are afraid of what the findings may reveal. 

Evidence of effectiveness? 

What does the best body of evidence show at this time? To answer this, we are left to debate this using research principally on respiratory influenza viruses or similar, this being considered indirect evidence, albeit very applicable to COVID-19. Overall, the available research is of very poor methodological quality using largely indirect unadjusted evidence, and not the optimal clinical research that is needed. A major limitation is the use of the same evidence base by all reviews and thus arrival at similar findings. However, this low-quality evidence is useful enough to guide us. 

Dr. Anthony Fauci of the NIH/NIAID stated in March 2020as part of his COVID-19 role, “wearing a mask might make people feel a little bit better” but “it’s not providing the perfect protection that people think it is.” Then and now, he actually echoed scientific agreement, and this was in line with the World Health Organization’s guidance. 

Specifically, the World Health Organization (WHO) states that “the widespread use of masks by healthy people in the community setting is not yet supported by high quality or direct scientific evidence and there are potential benefits and harms to consider”. 

More specifically, research by CDC (May 2020) published in Emerging Infectious Diseases (EID) examined personal protective measures and environmental hygiene measures for the effectiveness of such measures in reducing transmission of laboratory-confirmed influenza in the community. Researchers focused on disposable surgical or medical (typical blue coloured) face masks and identified 7 studies involving influenza and influenza-like illness (ILI) and reported no significant reduction in influenza transmission with the use of face masks. Overall, there was no significant effect of face masks in the transmission of laboratory-confirmed influenza and these findings could potentially be extrapolated to SARS-CoV-2 virus. 

Researchers from the University of Oxford’s Center for Evidence-Based Medicine (CEBM) examined the evidence on mask effectiveness within the current highly charged backdrop of politics. They concluded that after nearly 20 years of preparedness for coming pandemics, the evidence on face mask use remains very conflicted and raised tremendous uncertainty today. They are asking why has the right applicable research not been conducted. They also speculate on the elevated rates of harms (infection) when using cloth face masks. They specifically looked at 6 RCTs in 2010 that examined face masks in respiratory viruses whereby 2 were in healthcare employees and 4 were in family and student groups. The trials for ILI showed very poor mask wearing compliance and seldom reported the harms of use. 

In 2013, CADTH which is the Canadian Agency for Drugs and Technologies in Health, stated: “No evidence was found on the effectiveness of wearing surgical face masks to protect staff from infectious material in the operating room, no evidence was found to support the use of surgical face masks to reduce the frequency of surgical site infections, and guidelines recommend the use of surgical face masks by staff in the operating room to protect both operating room staff and patients (despite the lack of evidence)”. 

Jefferson et al. studied physical interventions to interrupt or reduce the spread of respiratory viruses (updating a prior Cochrane review (2011) to now include 15 RCTs (n=13,259 persons) exploring the impact of masks (14 trials) in healthcare workers, the general population and those in quarantine (1 trial)). When compared to no masks, researchers found no significant reduction of ILI cases or influenza for masks in the general population and in healthcare workers. There was also no difference between surgical masks and N95 respirators for ILI or for influenza. The body of evidence was considered to be of ‘low’ quality based on included study limitation, for even though RCTs, they were plagued with serious methodological concerns. 

The New England Journal of Medicine (NEJM)  recently published an article on COVID-19 and masks which appeared to suggest that masks have become no more than a psychological crutch, and stated that “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”. 

A recent WHO sponsored systematic review and meta-analysis included 39 nonrandomized observational studies (weaker study designs) that were not always fully adjusted and reported that face masks could be effective. These studies were small sampled sized with small event numbers, and plagued with potential selection bias and residual confounding bias. The body of evidence was judged to be at low quality (low certainty) and were at risk of recall bias and measurement bias. Researchers principally assessed mask use in households or contacts of cases that reported on SARS and MERS epidemics (limited for COVID-19), but researchers argue that this indirect evidence can be regarded as the most direct information for COVID-19. Moreover, the Newcastle-Ottawa scale was used to rate risk of bias and this is presently regarded as outdated and lacks the coverage to adequately assess risk of bias in nonrandomized studies. The ROBINS-I tool is the more applicable risk of bias tool for nonrandomized studies and has been recently designed by Cochrane to address the limitations of prior tools such as the Newcastle-Ottawa scale. 

Researchers led by University of Toronto epidemiology professor Peter Jueni, have now come forward asking LANCET to retract the study, citing numerous serious methodological flaws such as (but not limited to): 

i) 7 studies are unpublished and non-peer-reviewed observational studies 

ii) the review failed to consider the randomized evidence 

iii) 25 included studies are about the SARS-1 virus or the MERS virus, both of which have very different transmission characteristics: they were transmitted almost exclusively by severely ill hospitalized patients and not by community transmission 

iv) of the 4 studies relating to the SARS-CoV-2 virus, 2 were misinterpreted by the Lancet meta-study authors, 1 is inconclusive, and 1 is about N95 (FFP2) respirators and not about medical masks or cloth masks and 

v) this review is used to guide global facemask policy for the general population whereby one included study was judged to be misclassified (relating to masks in a hospital environment), one showed no benefit of facemasks, and one is a poorly designed retrospective study about SARS-1 in Beijing based on telephone interviews. None of these studies refer to SARS-CoV-2.

Similarly, a recent study published in PNAS surrounding airborne transmission and facemasks has also provoked substantial consternation and argued to be a political study more than a scientific one. It has led to over 40 leading scientists to call for its withdrawal due to it being very flawed due to very sub-optimal statistical analyses. 

A review by the Norwich School of Medicine (preprint) looked at the effectiveness of wearing facemasks and examined 31 published studies of all research designs. They reported that “the evidence is not sufficiently strong to support widespread use of facemasks as a protective measure against COVID-19. However, there is enough evidence to support the use of facemasks for short periods of time by particularly vulnerable individuals when in transient higher risk situations”.

A recent Danish Study  published in the Annals of Internal Medicine sought to assess whether recommending surgical mask utilization outside of the home works to reduce the wearers’ risk of SARS-CoV-2 virus infection in a setting where masks were uncommon and not among recommended public health measures. They included a total of 3030 participants being randomly assigned to the recommendation to wear masks, and 2994 being assigned to the control arm; 4862 persons completed the study. Infection with SARS-CoV-2 occurred in 42 participants recommended masks (1.8%) and 53 control participants (2.1%). The between-group difference was −0.3 percentage point (95% CI, −1.2 to 0.4 percentage point; P = 0.38). Researchers concluded that the studied recommendation to wear a surgical mask when outside the home among others did not reduce new or incident SARS-CoV-2 infection when compared with a no mask recommendation. These results emerged in a setting where social distancing and other public health measures were in effect, mask recommendations were not among those measures, and community use of masks was uncommon. No doubt this study findings has serious implications for the drive for mandatory masking of populations.

Additionally, in regards to cloth face masks, recent reports suggest that they should never be used as a protective barrier as they offer no transmission protection (as PPE or as source control) e.g. a Tokyo report and BMJ study

In the BMJ cluster randomized study, researchers sought to compare the efficacy of cloth masks to medical masks in hospital workers (in 14 Vietnamese hospitals utilizing 1607 workers over 18 years if age). Wards were randomized to medical masks, cloth masks or to a control group of usual practice which did include wearing masks (masks used on every shift for 4 consecutive weeks). The rates of all infection outcomes were highest in the cloth mask arm, with the rate of ILI statistically significantly higher in the cloth mask arm (relative risk (RR)=13.00, 95% CI 1.69 to 100.07) compared with the medical mask arm. Cloth masks also had significantly higher rates of ILI compared with the control arm. An analysis by mask use showed ILI (RR=6.64, 95% CI 1.45 to 28.65) and laboratory-confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were significantly higher in the cloth masks group compared with the medical masks group. Researchers found that penetration of the cloth masks by particles were near 97% and for medical masks, it was 44%. This being the first RCT of cloth masks, the researchers cautioned against the use of cloth masks. There is extensive moisture retention and poor filtration with reuse results in increased risk of infection. Cloth masks should not be recommended for healthcare workers and especially in high-risk settings. 

The Norwegian Institute of public health (NIPH) conducted a recent rapid review to assess if individuals in the community without respiratory symptoms should wear facemasks to reduce the spread of COVID-19. They modelled that, assuming 20% are asymptomatic and with a risk reduction of 40% when wearing masks, that approximately 200,000 persons would need to wear a mask to prevent one new infection per week. Researchers concluded that based on the existing epidemic/pandemic in Norway, that “wearing facemasks to reduce the spread of COVID-19 is not recommended for individuals in the community without respiratory symptoms who are not in near contact with people who are known to be infected”.  They went on to report that only if the epidemiological situation worsens significantly in a geographical area, then the use of facemasks as a precautionary measure should be reconsidered.

In a May 2020 communication report in Nature (Medicine), Leung et al. examined the importance of respiratory droplet as well as aerosol routes of spread with a specific focus on coronaviruses, influenza viruses, and rhinoviruses. They quantified the quantity of respiratory virus in exhaled breath of participants with acute respiratory infections (ARIs) and determined the possible efficacy of surgical face masks to prevent respiratory virus transmission. As part of the study, they screened 3,363 persons in two study phases, eventually enrolling 246 participants who provided exhaled breath samples, with 122 (50%) of the participants being randomized to either not wearing a face mask during the first exhaled breath collection or randomized to wearing a face mask (n=124 (50%)). They identified seasonal human coronaviruses, influenza viruses and rhinoviruses within exhaled breath and coughs of children as well as adults with ARI. In this study, they found that surgical face masks can significantly reduce detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols, and with a trend toward reduced detection of coronavirus RNA in respiratory droplets. Overall, researchers concluded that aerosol transmission is a likely mode of transmission for coronaviruses as well as influenza viruses and rhinoviruses, their results suggestive that surgical masks can effectively reduce the release of influenza virus particles into the environment in respiratory droplets, but not in aerosols. 

In a recent NEJM publication (CHARM study), researchers looked at SARS-CoV-2 transmission among marine recruits during quarantine. Recruits (n=1848 of 3143 eligible recruits) who volunteered underwent a 2-week quarantine at home that was followed by a 2nd 2-week quarantine in a closed college campus setting. As part of the study, participants wore masks and socially distanced, and symptoms were monitored with daily checks of temperature. RT-PCR testing was used to assess the effectiveness of these strategies and nasal swab samples were collected between arrival and the 2nd day of supervised quarantine and on days 7 and 14 (the 2nd quarantine used to mitigate infection among recruits). All recruits were required to have a negative RT-PCR result prior to entering Parris Island. Researchers reported that within 2 days from arrival on the closed campus, 16 tested positive for SARS-CoV-2 (15 being asymptomatic) and 35 more tested positive on day 7 or on day 14 (n=51 in total). In addition, 5 (9.8%) of the 51 positive volunteers had symptoms in the week prior to a positive PCR test. Phylogenetic analysis was conducted whereby 6 independent monophyletic transmission clusters (independent viral strains) indicative of local transmission were uncovered, occurring during the supervised quarantine. The majority of clusters principally included members of the same platoon, and numerous infected recruits had an infected roommate. 

In conclusion, authors reported that about 2% who had earlier negative tests for SARS-CoV-2 at the beginning of supervised quarantine, and less than 2% of recruits who had unknown prior status, tested positive by day 14. Positive volunteers were mainly asymptomatic and transmission clusters occurred within platoons. The predominant finding is that despite the very strict and enforced quarantine (including 2 full weeks of supervised confinement and then forced social distancing and masking protocols), the result was a higher transmission rate and not a lower one. Masks not only did not work, but it appears it made things worse. Despite quarantines, social distancing, and masking, in this cohort of mainly young male recruits, roughly 2% still went on to become infected and tested positive for SARS-CoV-2. Sharing of rooms and platoon membership were reported risk factors for viral transmission. The study raises questions about the utility of quarantines as it appears they do not work even when supervised for 2 weeks in a closed college etc., and it seems that quarantines are ineffective. Masks do not work for even when under full time military supervision in a boot camp environment and the masking is enforced, it emerges as ineffective. Moreover, social distancing in very strict military boot camp conditions appear to be ineffective also in preventing infections. In this study when compliance was monitored and enforced, and the conditions are favourable enough to support a rigorous study, we find that the so called ‘mitigation’ strategies do not work. This study stands as one of the higher-quality more robust studies on the question of masking. 

What about possible harms from wearing masks? Is there any evidence of this? 

But what about harms from mask use? The harms and negative effects are accumulating, extensive, and very troubling especially as they pertain to risk to children. This given that evidence suggests that children do not readily acquire the COVID virus or spread it to other children or take the virus home or get seriously ill or die from it (which is opposite to children being the drivers of seasonal influenza and do go on to suffer morbidity and mortality from influenza far above what is visited upon them by COVID-19). The reports are even more directly applicable to COVID-19. The evidence is not optimal clinical comparative research and is principally media reporting. However, this in itself is evidence and credible direct evidence at that. What is accumulating involves mask wearers within a COVID-19 environment and raises many concerns. It suggests that masks can impair breathing, can cause inhalation of toxic substances such as microplastics and chlorine compounds located in the masks (serious risks), can potentially cause CO2 intoxication or sudden cardiac arrest seen in children, can cause psychological damage, can cause (N95 masks) a reduction in the PaO2 level, increased the respiratory rate, and increased the occurrence of chest discomfort and respiratory distress with prolonged use, and can cause dizziness and light-headednessheadaches. There appears to be a risk of toxic carbon-dioxide buildup as well as some deprivation of oxygen. Mask use can potentially lead to bacterial and mould buildup in children, can cause decaying teeth, receding gum lines and inflammation in gums, can lead to anxiety and sleep problems, behavioral disorders and fear of contamination in children, can cause mask mouth, and can even lead to car accidents. In addition, Stanford engineers report that masks can make it much more difficult to breathe, estimating that N95 masks as an example, reduce oxygen intake from 5% to 20% and if worn for a prolonged period, can damage the lungs and for a person in respiratory distress, it is life threatening. 

Predominant finding? 

The predominant conclusion by global nations is that face masks have a very important role in places such as hospitals, but there exists very little evidence of widespread benefit for members of the public (adults or children). Masks are basically better than nothing, not sealed properly to the face and do not effectively stop the virus. Policy must be undergirded by sound data, and the reality is that widespread use of masks is not supported by science. This mask hysteria is driving unnecessary fear in the population and must end. These people make relentless statements on the use of masks that have no credible basis. However, it is important to understand that as we await definitive research, given the situation and the desire to prevent spread to higher-risk persons (e.g. elderly), when consistent social distancing is not possible, and out of an abundance of caution, face coverings may reduce the spread of droplets from individuals with SARS-CoV-2 infection to others. This must also be considered when a setting is experiencing elevated transmission. 

It is very sensible that one would use a face mask when visiting an elderly person who is high-risk or even if the setting is controlled such as a healthcare one of nursing home. I stand by this and practice and advocate for this. Thus personally, if a situation is judged by me as a high-risk one and I cannot socially distance, I would wear a mask for the wellness of all involved, despite no evidence of its effectiveness as described above. It is reasonable to be cautions, even in the light of limited or non-existent evidence of effectiveness and strong evidence of harms. Situation-by-situation decisions pending on the risk at hand. The full context must be considered but if you are adequately socially distanced, there is no reason to wear a mask. There is no evidence for this. 

Very alarming is Danish reporting of a higher-quality mask study on COVID and masks being rejected by the top journals Lancet, New England Journal of Medicine, and the American Association’s JAMA. If this is proven true, it continues a pattern of politicization of the research and medical community more concerned in advancing their political ideologies, and potential bias by journal editors and the peer-review process. 

In closing, perhaps Yinon Weiss who is a U.S. military veteran, and who holds a degree in bioengineering from U.C. Berkeley, captures our current face-mask calamity by reminding us how masks constrain our return to a more normal life, which seems to be the aim of those using the pandemic for political ideology and election aims. It is potentially being used to medicalize us, to make us believe we are perennially very ill as a society and as such, drives fear. He eloquently states “Our universal use of unscientific face coverings is therefore closer to medieval superstition than it is to science, but many powerful institutions have too much political capital invested in the mask narrative at this point, so the dogma is perpetuated”.

To conclude this overview, this represents my look at the complete and most updated mask-related evidence and my personal opinion and decision. I am all for masks in high- risk settings when no other mitigation is possible and also for individual responsibility but there is no more effective substitute for this virus or any virus for that matter, than hand-washing hygiene. This is especially so given accumulating evidence out of Oxford (CEBM) of a fecal-oral route of COVID-19 transmission (taken together with fomite spread). Handwashing is one of the most effective actions we each can take to minimize spread of such respiratory viruses (common cold, influenza, COVID-19 virus etc.) that use the droplet and contact route to spread. One can even speculate that COVID-19 hand-washing will likely contribute to marked declines in influenza and other respiratory type illnesses globally this upcoming season. In sum, when we look at the science, there is emerging and troubling evidence of harms from mask use e.g. there is incorrect use, a complacency that emerges due to mask use and thus the relaxation of other mitigation steps, as well as mask contamination. Importantly, there are problems breathing when wearing masks.  There is no strong definitive evidence of benefits. There is no scientific basis for a broad mask mandate, anywhere. The evidence to support mask use is not available. We urge individual common-sense decisions and evidence-informed decisions by policy makers that take the data and science into account.


Dr. Paul Alexander, PhD (Oxford, McMaster, York University, and University of Toronto graduate and postdoc educated in a combination of epidemiology, research methodology, biostatistics, and evidence-based medicine/EBM)