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It’s Time to Truly Follow the Science, Starting With a Comprehensive Review of Masking Evidence


As a researcher grappling with public health challenges for over four decades, I’ve become dismayed that, at least when it comes to COVID-19, intuition or ideological bias often appear to impede rigorously following the science.

The pile-on backlash against a recently published “gold standard” systematic review of the evidence for masking further highlights this ongoing situation of confusion and groupthink.

Indeed, my experience in publishing this article appears indicative of such pervasive bias. In the hope of reaching many readers who wouldn’t necessarily agree with my conclusions, I had previously submitted this to many other media outlets. The fact that what would have been the first scientific critique that’s not simply a defensive dismissal of the mask review, published in a mainstream venue, was roundly rejected (including by one large magazine that held it up for a month, despite my agreeing to include ever more “nuance”) seems to further confirm the media’s reluctance to even discuss, in a more even-handed way, such important research findings.

Until April 2020, most scientists (including Dr. Anthony Fauci) correctly reported that the preponderance of the strongest evidence—based primarily on meta-analyses of findings from randomized controlled trials (RCTs)—indicated that masks provide limited protection against most respiratory viruses. Yet that month, the U.S. Centers for Disease Control and Prevention (CDC) and other public health authorities proclaimed that masks were suddenly an essential intervention, calling them a “proven highly effective” method.

Other than observing that the coronavirus seemed to be spreading less in East Asian countries where masking is common during the winter, no new data was presented to justify this newfound policy conclusion, one seemingly driven by political and bureaucratic expediency. As coronavirus expert Michael Osterholm, who has advised President Joe Biden, observed, “Never before in my 45-year career have I seen such a far-reaching public recommendation issued by any governmental agency without a single source of data or information to support it. This is an extremely worrisome precedent of implementing policies not based on science-based data or why they were issued without such data.”

Since then, many masking studies—no matter how theoretical in nature or questionable in their methodologies—that suggest any amount of benefit have been hailed by experts.

Meanwhile, when considerably stronger data eventually emerged, especially from randomized trials, indicating that masking did little to stop the spread of COVID-19, this was either ignored or repackaged to support the prevailing wisdom. A 2020 Danish RCT, which found no statistically significant evidence that wearing surgical masks protected wearers, went remarkably unnoticed (unmentioned, for example, on the CDC’s website, which, however, lists many weaker, often non-peer-reviewed observational masking studies). While some mask proponents have recently characterized the Danish data’s hint of effectiveness as constituting “encouraging evidence,” claiming the sample size was simply too small to find a significant effect, impartial scientists would dismiss this as merely wishful thinking.

Another RCT, conducted in Bangladesh and designed to measure community-level impact, was published in 2021 in Science. This very large study found absolutely no statistical benefit from typical cloth masks and only modest benefit (a reduction in self-reported COVID symptoms from 8.6 percent to 7.6 percent) from harder-to-use surgical devices. Although usually unmentioned in discussions of the study, a careful reanalysis detected compelling evidence of systematic bias. Yet the published results continue to be presented by the researchers and widely echoed by commentators as “definitive proof” that masking works.

On Jan. 30, the Cochrane Collaboration, highly regarded (at least until last month) for its thorough systematic reviews, published a much-awaited update of their meta-analysis of masking and other physical methods to prevent COVID-19 as well as other respiratory illnesses, finding no solid evidence for masking—not even for presumably higher-quality N95 respirators. A New York Times columnist created a stir when he claimed the Cochrane report confirms that community mask mandates were unnecessary and ineffective. But based on most of the scientific evidence so far, that seems to be the case.

The Cochrane meta-analyses adhere to a standardized methodology and undergo close review by the Collaboration, above and beyond the usual scientific peer review process. Cochrane reviews had been considered the gold standard for resolving controversies in medicine, especially when individual studies may have reported inconsistent or inconclusive results. As Dr. Robert Wachter, former chair of the American Board of Internal Medicine, told the New York Times in 2014, “When clinicians are debating the right thing to do, all someone needs to say is, ‘There’s a Cochrane review about that,’ and the argument ends.”

Yet despite the rigor of the Cochrane reviews, a spirited attempt has attempted to challenge this one‘s conclusion that “Wearing masks in the community probably makes little or no difference” to COVID-19 or other respiratory virus outcomes. Some critics contend that the meta-analysis lumped apples with oranges, by including studies conducted in different settings that assessed somewhat different interventions or outcomes. Yet this is typical for such meta-analyses, and the investigators utilized appropriate procedures to address these kinds of differences. Their review included 12 RCTs that compared masking versus no masking, involving hundreds of thousands of participants, as well as five trials of respirators versus simpler masks.

No methodology is perfect, not even the Cochrane’s, but if masks were anywhere near as effective as is widely claimed, for COVID-19 and other respiratory infections, this meta-analysis should have shown at least some degree of benefit. (The review did find a small but statistically significant effect from hand washing.)

As the Cochrane review’s Oxford University lead investigator Tom Jefferson (also first author of a highly influential Cochrane review of the controversial influenza medication Tamiflu) explained in a recent interview, “There is just no evidence that [masks] make any difference. Full stop. Our job as a review team was to look at the evidence, we have done that.”

In fact, the review’s conclusions are consistent with the physical limitations of masks—even “95 percent effective” N-95 devices appear to filter out only about half of particles—as well as the probably even more important reality that, unlike other health interventions such as condoms, masks need to be worn continually and correctly often for many hours at a stretch.

Little in science is totally conclusive, and the Cochrane researchers can’t and didn’t definitively conclude masks don’t work. Yet their review does call into serious question the commonplace assumption and official recommendations over the last three years that, with absolute certainty, masks do provide considerable protection. That’s even true for the persistent contention that masks definitely work at the individual level, for which as the Cochrane reviewers document there just isn’t any conclusive data. (Many recent Cochrane skeptics cite a CDC observational study as proof of individual protection, but this non-peer-reviewed paper had serious methodological weaknesses, such as an absurdly low response rate of around 10 percent.) And other commonsensical but data-weak notions should also be questioned, such as assuming that East Asian countries have fared better in part because of universal masking. Indeed, a year ago, Hong Kong had the world’s highest COVID-19 death rate at the time despite enforcing the harshest masking fines anywhere. (Whereas in Sweden, where masking and most other pandemic measures were never implemented, total mortality has remained—unlike in most countries—at near-normal levels throughout most of the pandemic.)

After three long years, it’s past time that we truly follow the science when it comes to our approaches to COVID-19. In addition to heeding an evidence-based approach to masking, the CDC could develop, as I and others have argued, a more rigorous method of categorizing COVID-19 hospitalizations and mortality. Los Angeles County, for example, has been defining COVID-19-associated illness as those patients testing positive who either have pneumonia, acute respiratory distress syndrome, or an acute cardiopulmonary diagnosis. Instituting a similar national standard, including for COVID-19 mortality statistics, would help toward attaining a more accurate assessment. Hopefully, the imperative to pursue a genuinely evidence-based approach (pdf) will finally overcome the ongoing defensiveness or ideological resistance to truly following the science.

Views expressed in this article are the opinions of the author and do not necessarily reflect the views of The Epoch Times.

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