The most rigorous and comprehensive analysis of scientific studies conducted on the efficacy of masks for reducing the spread of respiratory illnesses — including Covid-19 — was published late last month. Its conclusions, said Tom Jefferson, the Oxford epidemiologist who is its lead author, were unambiguous.
“There is just no evidence that they” — masks — “make any difference,” he told the journalist Maryanne Demasi. “Full stop.”
But, wait, hold on. What about N-95 masks, as opposed to lower-quality surgical or cloth masks?
“Makes no difference — none of it,” said Jefferson.
What about the studies that initially persuaded policymakers to impose mask mandates?
“They were convinced by nonrandomized studies, flawed observational studies.”
What about the utility of masks in conjunction with other preventive measures, such as hand hygiene, physical distancing or air filtration?
“There’s no evidence that many of these things make any difference.”
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.
