Face masks in the covid-19 crisis: caveats, limits, and priorities

john.middleton@aspher.org We agree with Greenhalgh and colleagues that decision making should be based on scientific knowledge, but when knowledge is incomplete, as in the current pandemic, judgments based on precaution and pragmatism become increasingly necessary.1 The Association of Schools of Public Health in the European Region’s report launched on 24 April recommends the use of face masks by the general public, with clear caveats, limits, and priorities.2 Non-medical grade “social” masks must be one element alongside other non-pharmaceutical measures (personal hygiene, physical distancing, and so on). Masks should be used from the consolidated start of the decline in contagion as part of a phased reduction of lockdown measures and a return to economic activity. If widespread use of masks is implemented, there must be a strong public training campaign by health authorities with quality assurance processes.