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That NEJM article is about the benefits (or lack) to health care workers. They don't address community masks except to brush it off: "We know that wearing a mask outside health care facilities offers little, if any, protection from infection. "

They give the reason: "The chance of catching Covid-19 from a passing interaction in a public space is therefore minimal." It takes many minutes of interaction. Like the church choir (two hours) or the beauty parlor (30 minutes or more). There was no spread in the beauty parlor because most people were wearing masks. You can ignore that. Or you can give an explanation. Your choice.