evidence: Yes, Wearing Masks Helps. Here's Why [...] Researchers emphasize there are two main reasons to wear masks. There's some evidence of protection for the wearer, but the stronger evidence is that masks protect others from catching an infection from the person wearing the mask. And infected people can spread the virus just by talking. [...] Other recent studies offer indirect evidence for universal mask use, even if worn by people who are feeling healthy. One study, published in late May in BMJ Global Health, looked at people in households in Beijing where one person was confirmed to have COVID-19. At the time, explains study co-author Raina MacIntyre, research was already showing that the majority of transmission of the virus was happening inside households, and China already had a culture of mask wearing. The study found that in households where everyone was wearing a face mask indoors as a precaution before they knew anyone who lived there was sick, the risk of transmission was cut by 79%.