People who wear multilayer cloth masks protect not only the people they encounter from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) but also themselves, according to an updated scientific brief from the US Centers for Disease Control and Prevention (CDC). Previous recommendations from the CDC advising people to wear cloth masks stressed evidence that the practice helps with source control—that is, preventing people infected with SARS-CoV-2, including those without symptoms, from spreading the virus to others. Individuals with infections who are presymptomatic or asymptomatic are estimated to be the source of more than half of SARS-CoV-2 transmissions, the agency has noted.