These observations don’t come from just anywhere. Jefferson and 11 colleagues conducted the study for Cochrane, a British nonprofit that is widely considered the gold standard for its reviews of health care data. The conclusions were based on 78 randomized controlled trials, six of them during the Covid pandemic, with a total of 610,872 participants in multiple countries. And they track what has been widely observed [cites omitted — ed.] in the United States: States with mask mandates fared no better against Covid than those without.
No study — or study of studies — is ever perfect. Science is never absolutely settled. What’s more, the analysis does not prove that proper masks, properly worn, had no benefit at an individual level. People may have good personal reasons to wear masks, and they may have the discipline to wear them consistently. Their choices are their own.
But when it comes to the population-level benefits of masking, the verdict is in: Mask mandates were a bust. Those skeptics who were furiously mocked as cranks and occasionally censored as “misinformers” for opposing mandates were right. The mainstream experts and pundits who supported mandates were wrong. In a better world, it would behoove the latter group to acknowledge their error, along with its considerable physical, psychological, pedagogical and political costs.
As Kelsey Piper observes, this is substantially overstated:
I think Jefferson — an Oxford University epidemiologist who has a number of eccentric and flatly nonsensical opinions about Covid-19, including that it didn’t originate in China and may have been circulating in Europe for years before its global emergence — is overstating his case. There is something we can learn from the Cochrane paper, but it’s as much about the process of science as it is about the effectiveness of masks.
First, the reasons I don’t totally buy the Cochrane review’s conclusions:
The review includes 78 studies. Only six were actually conducted during the Covid-19 pandemic, so the bulk of the evidence the Cochrane team took into account wasn’t able to tell us much about what was specifically happening during the worst pandemic in a century.
Instead, most of them looked at flu transmission in normal conditions, and many of them were about other interventions like hand-washing. Only two of the studies are about Covid and masking in particular.
Furthermore, neither of those studies looked directly at whether people wear masks, but instead at whether people were encouraged or told to wear masks by researchers.If telling people to wear masks doesn’t lead to reduced infections, it may be because masks just don’t work, or it could be because people don’t wear masks when they’re told, or aren’t wearing them correctly.
There’s no clear way to distinguish between those possibilities without more original research — which is not what a meta-analysis of existing work can do.
Those studies that did take on Covid and masks directly often painted a different picture than the broader conclusions from the meta-analysis.
One of the largest studies of mask-wearing during the Covid pandemic was conducted in Bangladesh, with more than 170,000 people in the intervention group and similar numbers in the control group. The authors studied a series of public announcements and mask distributions which raised the frequency of mask-wearing. In the end, around 40 percent of the experimental group wore masks, compared to around 10 percent in the control group.
The result, the study found, was a substantial reduction in the share of people with Covid-19-like symptoms, and in antibodies that would suggest a Covid-19 infection: “In surgical mask villages, we observe a 35.3% reduction in symptomatic seroprevalence among individuals ≥60 years old … We see larger reductions in symptoms and symptomatic seropositivity in villages that experienced larger increases in mask use.”
That looks like pretty substantial evidence that mask-wearing reduces Covid-19! And this article is one of only two studies of mask-wearing included in the Cochrane review which happened during the Covid-19 pandemic. The other, a study in Denmark, assigned people to wear masks (though, of course, not all of the people told to wear masks did so consistently or correctly) and had a control group that generally did not wear masks. The group that was told to wear masks had slightly lower infection rates than the group that didn’t wear masks, but the sample was too small for the effect to be significant.
Given that — one study finding very solid evidence for the benefits of masks, and one finding limited but encouraging evidence — how did Cochrane arrive at its conclusion that mask wearing “probably makes little or no difference?” Because their meta-analysis mixes these studies with many more pieces of research that were conducted before Covid-19 and found little effect of masks on the transmission of other illnesses like influenza.
Even if we assume arguendo that mask mandates as implemented in the United States were not very effective — very possible, although it is far from an established fact — the apparent paradox between good, properly-worn masks being effective at an individual level but mask mandates not being very effective is fairly easily resolved. Even in deep blue jurisdictions, mask mandates were not enforced by even mild state coercion, there was little-to-no attempt to provide people with N-95-quality masks, even people making a good faith effort to comply with the mandates often wore poor quality masks and/or wore them improperly, and they were constantly being undermined by people with large platforms like Stephens asserting that it was impossible for COVID to be widespread outside of a few dense urban areas.
“Poorly conceived and executed policies were ineffective” is, even if it proves true, very different than “masks don’t work,” but I have no doubt that people like Stephens will be successful at conflating these points in the public mind, which will make it harder to respond to the next pandemic.