evidence: Adams’ advice was in line with messages from other US officials and the World Health Organization. Days later, though, US public health leaders shifted course. Mask-wearing was soon a pandemic-control strategy worldwide, but whether this strategy succeeded is now a matter of heated debate—particularly after a major new analysis, released in January, seemed to conclude that masks remain an unproven strategy for curbing transmission of COVID-19 and other respiratory viruses. "There’s still no evidence that masks are effective during a pandemic," the study’s lead author, physician, and epidemiologist Tom Jefferson, recently told an interviewer. [...] For some, the Cochrane review provided vindication. "Mask mandates were a bust," conservative columnist Bret Stephens wrote in The New York Times last week. "Those skeptics who were furiously mocked as cranks and occasionally censored as ‘misinformers’ for opposing mandates were right."