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Opinion editor's note: Editorials represent the opinions of the Star Tribune Editorial Board, which operates independently from the newsroom.

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The human mind is ill at ease with ambiguity, with imperfect solutions and, especially, with being told to think what it isn't inclined to think.

That's perhaps why a researcher who believes that the effectiveness of wearing face coverings to prevent disease has not yet "been given a proper trial" is nonetheless willing to say that it "makes no difference — none of it," not even N95 respirators, and why others who just knew it all along are happy to add: "I told you so."

So that's that? Masks have been useless against COVID? "There's no evidence that they do work — that's right," says Tom Jefferson. "It's possible they could work in some settings … we'd know if we'd done trials."

Jefferson is lead author of a recent Cochrane review, "Physical interventions to interrupt or reduce the spread of acute respiratory viruses." Cochrane is a respected nonprofit that does meta-analysis — essentially, studies of studies — in an attempt to figure out what, if anything, conclusive can be found among disparate research into what works and what doesn't.

Such an approach can improve confidence, but it doesn't necessarily clear away caveats. That Cochrane's work is a "gold standard," as characterized in a recent commentary by New York Times columnist Bret Stephens that was republished by Star Tribune Opinion, is not a universal view, as evidenced by Minnesota epidemiologist Michael Osterholm on a recent podcast. In Osterholm's view, it still involves people, and thus bias.

In this case, it also still involves plenty of ambiguity: What kind of masks were studied? What kind of discipline in using them? What was the quality of the research?

Cochrane's look at masking and other disease precautions took in 78 studies. It updated a 2020 review, adding six done during the pandemic to the bulk done before the COVID era. If there's an overarching conclusion, it's that Cochrane didn't have much confidence in the methodology it encountered. Money quote: "The high risk of bias in the trials, variation in outcome measurement, and relatively low adherence with the interventions during the studies hampers drawing firm conclusions."

Osterholm and colleagues at the Center for Infectious Disease Research and Policy at the University of Minnesota have further critiques at tinyurl.com/cidrap-masks. Essential advice: If you're in a position of risk, wear an N95.

The Cochrane study also didn't deter the World Health Organization from reiterating that masks are effective. Maria Van Kerkhove, WHO's technical lead for COVID-19, said the organization looks at all available evidence.

But Jefferson's decisive tone, amplified by Stephens, gave fresh energy to sentiment against masks and, in particular, mask mandates. Jefferson, a University of Oxford epidemiologist, called such policies "a complete subversion of the 'precautionary principle,' which states that you should do nothing unless you have reasonable evidence that benefits outweigh the harms."

We suppose that's "first do no harm" in a nutshell. However, inaction can also cause harm. At the start of it all in 2020, the world didn't know exactly what it had on its hands. A new virus was spreading rapidly and killing efficiently. That's exactly the scenario in which it's wise to withdraw, assess and grab what defenses are available. The world knew little about COVID-19 then but could expect to know much more with time. Vaccines were a hope on the horizon.

Did mask mandates cause harm? No, they caused inconvenience to many, annoyance to some. Closing schools to in-person learning, on the other hand, did visible harm to students. Yet even there the counterfactual is hard to pin down — that if schools had been left open at that point, they wouldn't have been a locus of transmission.

It's smart to scrutinize such responses in the hope of improving them next time around. From the looks of it, an opportunity to study masking in the crucible of a live pandemic was missed. It's not too late to learn more, and the Cochrane review is a start.

For a brief while in the early stages of the pandemic, there was unity in the public response. Would society be as proactive again? COVID mutations are unpredictable. Vaccine uptake is dwindling. Meanwhile, a broad outbreak of bird flu has been spreading uncharacteristically among mammals. It's not reaching people but could have a high fatality rate if it did.

Meanwhile, COVID still kills hundreds of Americans each day. You know, in case you lost track.