Face masks during the COVID-19 pandemic

During the COVID-19 pandemic, face masks or coverings, including N95, FFP2, surgical, and cloth masks, have been employed as public and personal health control measures against the spread of SARS-CoV-2, the virus that causes COVID-19.

In community and healthcare settings, their use is intended as source control to limit transmission of the virus and for personal protection to prevent infection.[1] Properly worn masks both limit the respiratory droplets and aerosols spread by infected individuals and help protect healthy individuals from infection.[2][3]

Reviews of various kinds of scientific studies have concluded that masking is effective in protecting the individual against COVID-19.[2][4][5] Various case-control and population-based studies have also shown that increased levels of masking in a community reduces the spread of SARS-CoV-2,[4][5] though the evidence from randomized controlled trials (RCTs) has been inconclusive as to whether mask policies reduce spread on a population level.[6] Masks vary in how well they work, with N95 and surgical masks outperforming cloth masks, which as of 2021 were more common due to supply shortages,[7] but even cloth masks, with their variability in fabric type and mask fit, provide wearers with substantial protection from particles carrying COVID-19.[8]

Among readily available fabrics, double-layered cotton, hybrid masks, and cotton flannel perform best,[8] and filtration effectiveness generally improves with thread count.[7] Healthcare workers, given their exposure, are recommended against using cloth masks.[8]

During the emergency phase, governments widely recommended and mandated mask-wearing. Prominent national and intergovernmental health agencies and their leaders have recommended the use of masks to reduce transmission, including the WHO, American, European, and Chinese Centers for Disease Control and Prevention.