One of the most politicised scientific issues of 2020 was the question about whether face-masks stop the spread of COVID-19. I trust we can agree that this is notable without requiring specific examples.
When worn by health care workers (e.g. in the context of hospitals) who are infected, are N95 respirators effective at slowing the spread of COVID-19?
Note that this question is about effectiveness (not efficacy), so answerers and voters are invited to weight evidence about the spread of COVID-19 in real-life conditions above evidence from lab experiments, and in turn, evidence from lab-experiments above theoretical models.
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