New study provides the “definitive answer on masks.” They work.

Jennifer Sandlin  3:33 am Fri May 24, 2024

 Masks WORK! Photo: Jennifer Sandlin

I’ve masked consistently since the beginning of the ongoing COVID-19 pandemic, first with a cloth mask, before I knew better, and then for the last few years with KN95s or N95s. And I have, to my knowledge, continued to avoid catching the virus. In fact, I haven’t been sick for at least 4.5 years, and I attribute that in large part to masking. I also opt for patios if I go out to eat, if at all possible, so that’s also part of why I haven’t been sick. But it’s also definitely the masking. Needless to say, I’m already a huge believer in the science of masking. In simple terms: masks work. 

Masks and respirators for prevention of respiratory infections: a state of the science review [journals.asm.org]

However, it’s hard to convince folks who have swallowed the fake news that masking is harmful or that masks don’t work. I won’t link to those (flawed) “studies” because I definitely don’t want to share more misinformation, but suffice it to say, folks who believe masks don’t work are either not reading actual science, or aren’t actually masking, or aren’t using high quality masks, or if they are wearing masks, aren’t wearing them properly (yeah, you’re right, masks around your chin don’t actually work!). 

In case you still have the patience to try to convince a mask skeptic—or even a rabid anti-masker—that masks *do* actually work, here’s a great, brand-new, peer-reviewed study to share with them. The paper, which is based on a narrative review and meta-analysis research project, was written by an international team of 13 researchers from universities including University of Oxford (UK), University of New South Wales (Sydney, Australia), University of Toronto (Canada), University of Otago (Wellington, New Zealand), and University of Calgary (Alberta, Canada). 

The paper synthesizes evidence from over 400 studies in total, including 100 published reviews, as well as primary studies from disciplines such as epidemiology, public health, engineering, and social studies—all of which focused on the exploring the efficacy of masking. The authors explain that they even re-analyzed “contested meta-analyses of key clinical trials”—including the infamously controversial Cochrane review. In fact, the authors state specifically that their review “was commissioned partly because of controversy around a Cochrane review which was interpreted by some people as providing definitive evidence that masks don’t work.” However, that’s never what the Cochrane review actually stated, as explained by the authors of this current review:

The need for a new review on masks was highlighted by a widely publicized polarization in scientific opinion. The masks section of a 2023 Cochrane review of non-pharmaceutical interventions (9) was—controversially—limited to randomized controlled trials (RCTs). It was interpreted by the press and by some but not all of its own authors to mean that “masks don’t work” and “mask mandates did nothing” (10). Cochrane’s editor-in-chief felt the need to state publicly that in Cochrane’s view, the review’s findings did not support such a conclusion (11). Some scholars were quick to question the review’s methodology, especially key flaws in the meta-analysis and omission of a vast body of non-RCT evidence (12–16).

I, for one, am thrilled that this study explicitly addresses—and debunks—the Cochrane review, because that single study probably did more damage than almost anything else to widespread attempts to get people to mask to keep themselves and others safe from COVID-19. 

The authors of this new review found evidence that led them to seven main findings:

First, there is strong and consistent evidence for airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory pathogens. 

Second, masks are, if correctly and consistently worn, effective in reducing transmission of respiratory diseases and show a dose-response effect. 

Third, respirators are significantly more effective than medical or cloth masks. 

Fourth, mask mandates are, overall, effective in reducing community transmission of respiratory pathogens. 

Fifth, masks are important sociocultural symbols; non-adherence to masking is sometimes linked to political and ideological beliefs and to widely circulated mis- or disinformation. 

Sixth, while there is much evidence that masks are not generally harmful to the general population, masking may be relatively contraindicated in individuals with certain medical conditions, who may require exemption. Furthermore, certain groups (notably D/deaf people) are disadvantaged when others are masked. 

Finally, there are risks to the environment from single-use masks and respirators. 

The authors also provide some recommendations for future research:

We propose an agenda for future research, including improved characterization of the situations in which masking should be recommended or mandated; attention to comfort and acceptability; generalized and disability-focused communication support in settings where masks are worn; and development and testing of novel materials and designs for improved filtration, breathability, and environmental impact.

University of Calgary News recently published an overview of the study which included some discussion of the study by lead author Professor Trisha Greenhalgh from the Nuffield Department of Primary Care Health Sciences, University of Oxford, who stated, “Our review confirms that masks work, with a clear dose-response effect. . . The more consistently and correctly you wear a mask, the better protected you are. Respirators, when worn continuously, provide even greater protection than ordinary masks.”

Co-author Dr. Joe Vipond, MD and Associate Professor at University of Calgary’s Cumming School of Medicine also commented on the study, stating that it is the “definitive answer on masks”:

“In a world of misinformation, questioning the effectiveness of everything from masking to vaccines, it’s important to have solid science to support any assertion . . . This is the definitive answer on masks, looking beyond the narrow view of randomized controlled trials to the entirety of the evidence. And behold, the current science upholds the standards and protocols that for decades have protected health care workers, and more recently the public, from biohazards.” 

I know it would be naive to think that this robust study on the efficacy of masking will change die-hard anti-maskers’ minds. But perhaps it will persuade some people who are still open to learning from actual data. Here’s hoping, anyway! Mask up, folks! And if you’re looking for me, I’m the one in the hot pink mask!

Click here to read the full study and here to read the rest of the summary and interviews with several of the authors from University of Calgary News