april 2020 • The BMJ

Face masks for the public during the covid-19 crisis

Trisha Greenhalgh, Manuel B Schmid, Thomas Czypionka, et al.

DOI: 10.1136/bmj.m1435

Content curation::David Rodrigues

Key message

A eficácia das máscaras na redução da transmissão da covid-19 no público em geral é incerto e alvo de discussão científica. O princípio da precaução pode ser usado para fundamentar recomendações num contexto de ausência de evidência definitiva. Mesmo uma proteção limitada pode impedir a transmissão de covid-19 e eventualmente salvar vidas; Sendo a covid-19 uma ameaça séria, usar máscaras em público deve ser recomendado.

Abstract

The precautionary principle is, according to Wikipedia, “astrategy for approaching issues of potential harm when extensivescientific knowledge on the matter is lacking.” The evidencebase on the efficacy and acceptability of the different types offace mask in preventing respiratory infections during epidemicsis sparse and contested. But covid-19 is a serious illness thatcurrently has no known treatment or vaccine and is spreadingin an immune naive population. Deaths are rising steeply, andhealth systems are under strain.This raises an ethical question: should policy makers apply theprecautionary principle now and encourage people to wear facemasks on the grounds that we have little to lose and potentiallysomething to gain from this measure? We believe they should.