ScienceMasks are effective!To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 videoScience09/15/2021September 15, 2021Masks are effective and limit the spread of COVID-19. That's the result of the largest study of masks ever involving more than 340,000 people across 600 rural villages.https://p.dw.com/p/40Mc5Advertisement