a systematic review and meta-analysis Derek K Chu et al. on behalf of the COVID-19 Systematic Urgent Review Group Effort (SURGE) study authors. Published: The Lancet June 01, 2020 DOI: https://doi.org/10.1016S0140-6736(20)31142-9 'We did a systematic review of 172 observational studies in health-care and non-health-care settings across 16 countries and six continents... Physical distancing of 1 m or more was associated with a much lower risk of infection, as was use of face masks (including N95 respirators or similar and surgical or similar masks [eg, 12–16-layer cotton or gauze masks]) and eye protection (eg, goggles or face shields)...'