In a recent interview with The New York Times, former White House COVID-19 adviser Anthony Fauci conceded that face masks had, at best, a modest overall impact on coronavirus transmission during the pandemic. “From a broad public-health standpoint, at the population level, masks work at the margins—maybe 10 percent,” he said. “But for an individual who religiously wears a mask, a well-fitted KN95 or N95, it’s not at the margin. It really does work.”
This week CNN’s Erin Burnett asked Surgeon General Vivek Murthy about Fauci’s gloss, which she said might be perceived as “an extremely significant statement,” because “we were told it didn’t matter what kind of mask [we wore].” She also noted that children were required to wear masks in schools and day care centers, adding that “none of them wore them the right way.” The contrast between that frequently mandatory advice and what Fauci is saying now, Burnett suggested, is “upsetting to a lot of people.”
Murthy’s response illustrates the persistent difficulty that public health officials have in speaking honestly about this subject. He conceded that shifting government health advice “can be disconcerting” but said “sometimes guidance does evolve over time as you learn more.” He also allowed that the pandemic “has been incredibly hard for a lot of people, especially kids and parents.” And he mentioned “greater loneliness and isolation” as one consequence of the pandemic, saying the Biden administration is working on “a national strategy to address loneliness.”
The one thing Murthy did not address was the substance of Burnett’s question. Fauci’s current summary of the evidence, she noted, contradicts what public health officials told us during the pandemic. “Do you understand,” Burnett asked, why people might view that contradiction as “extremely significant” and “upsetting”? Murthy evidently does not understand that, even though it goes to the heart of the government’s credibility when it purports to tell us what science says about the effectiveness of disease control measures.
Murthy’s claim that the government’s repeatedly revised mask guidance was driven by compelling new evidence is hard to take seriously. There was no such new evidence when the Centers for Disease Control and Prevention (CDC), after dismissing the value of general masking early in the pandemic, decided it was “the most important, powerful public health tool we have.” There was no such evidence when the CDC belatedly acknowledged that N95s were superior to cloth masks. Or when the CDC belatedly decided it was time to lift mask mandates in schools.
For most of the pandemic, the CDC drew no distinction between the “well-fitted KN95 or N95” that Fauci says “really does work” and the cloth masks that people commonly wore in response to mandates. Based on shaky evidence, the CDC made extravagant claims about the general effectiveness of masks in reducing the risk of infection. And it never conceded what Fauci now admits: that there is a big difference between the individual benefits for someone who consistently and correctly wears the best kind of mask and the benefits that can be detected “at the population level” among people who typically don’t.
That point, which is crucial in evaluating the merits of mask mandates, was highlighted by the recent Cochrane Library review of 18 randomized controlled trials (RCTs) that aimed to measure the effectiveness of surgical masks in reducing the spread of respiratory viruses. Judging from those studies, the Cochrane review found, masking in public places “probably makes little or no difference” in the number of infections. The review said that conclusion was based on “moderate-certainty evidence.”
The authors suggested several possible explanations for the results of their meta-analysis, including “poor study design,” weak statistical power “arising from low viral circulation in some studies,” “lack of protection from eye exposure,” inconsistent or improper mask use, “self-contamination of the mask by hands,” “saturation of masks with saliva,” and increased risk taking based on “an exaggerated sense of security.” It is possible that some subjects in these studies did derive a benefit from wearing masks, but that effect was washed out by the behavior of other subjects who did not follow protocol, especially if those subjects took more risks than they otherwise would have because masks gave them “an exaggerated sense of security.”
When Fauci said general masking can reduce infections “at the margins” by “maybe 10 percent,” he seemed to have in mind the Bangladesh RCT mentioned by his interviewer, David Wallace-Wells. “In what was probably our best study, from Bangladesh, in places where mask use tripled, positive tests were reduced by less than 10 percent,” Wallace-Wells said.
The authors of the Cochrane review noted several weaknesses in the Bangladesh RCT, including “baseline imbalance, subjective outcome assessment and incomplete follow-up across the groups.” But that study accounted for a large share of the data in the meta-analysis and did not change the overall results, which indicated “little or no effect of mask use.”
Does the Cochrane review show that masks are useless? No. Laboratory studies provide reason to believe that masks, especially N95s, can protect both the wearer and the people he encounters. But those studies were conducted in stylized conditions that bear little resemblance to the real world. And the observational studies touted by the CDC, unlike the RCTs, were not designed to control for all the variables that might independently affect the risk of infection or transmission.
The advantage of properly designed RCTs is that they avoid both of those problems by randomly assigning subjects to mask and no-mask groups in real-world conditions. Yet as the Cochrane review shows, those studies do not support the claim that encouraging or requiring general masking has a substantial impact on the number of infections.
Critics of the review have argued that better-designed studies might detect a significant effect. But the fact remains that governments required children and adults to wear masks without firm evidence indicating that such policies would make an important difference. And even if you join Fauci in taking the Bangladesh study at face value, it is not reasonable to expect more than a modest effect.
The CDC, of course, did not get into any of this. Based on observational and laboratory studies with widely recognized weaknesses, it claimed that wearing a mask—any mask, apparently—”reduc[es] your chance of infection by more than 80 percent.” It even claimed, based on a statistically insignificant result from a deeply flawed observational study, that wearing a cloth mask “lowered the odds of testing positive” by 56 percent.
Nor did the CDC have any reservations about trumpeting the supposed benefits of mask mandates, without regard to whether studies controlled for confounding variables or even whether they included a comparison group at all. It was especially aggressive in promoting school and day care policies that required children as young as 2 to wear masks, pretending that the scientific case for them was overwhelming.
Leaving aide the methodological problems that the CDC ignored, its claims about the effectiveness of those mandates were inherently implausible for the reason that Burnett mentioned in her interview with Murthy: If adults typically do not wear masks consistently and properly, how likely is it that toddlers, elementary school students, and teenagers will do so? Not very, as anyone who observed masked students or saw photos of them could confirm.
Unsurprisingly, Murthy does not want to talk about all the ways in which public health officials like him systematically exaggerated the strength of the evidence in favor of mask mandates. He prefers to discuss “a national strategy to address loneliness.” But refusing to acknowledge the public health establishment’s credibility problem will not make it go away.
