COVID-19: did the masks work?

During the early stages of the COVID-19 pandemic, we called for mandatory public masking to 'flatten the curve'. We helped formulate a national standard (SWiFT 19) for barrier facemasks, and, using a novel laser-based approach, we determined that mask efficacy is dependent on both fabric and fit; with both variables being inversely related. Herein, we take a retrospective view of the role of masks during the pandemic and surmise that, on the balance of evidence to date, masks were effective at stemming the spread of SARS-CoV-2 and may well be an effective early control strategy for potential future respiratory pandemics. Face coverings, which cover the nose and mouth, are a means of preventing infections that travel in the air. These include viruses such as SARS-CoV-2, which causes COVID-19. Face coverings, or masks, played a key role during the COVID-19 pandemic by reducing person-to-person spread of the virus. The key features of a mask that make it effective are the material from which it is made and how closely the mask fits the face. A loosely fitting mask, for example, will lead to gaps around the nose and cheeks through which droplets can escape. A better fitting mask will have less leakage. Masks made from light single-layer material is less able to prevent droplet penetration than thicker, multi-layered fabric. Properly fashioned and fitted face masks are an effective means of slowing the spread of infections that travel in the air.