Unless we are talking about fitted N95 masks, CDC used to say the opposite even about transmission to others: "There is limited evidence for their effectiveness

Unless we are talking about fitted N95 masks, CDC used to say the opposite even about transmission to others: "There is limited evidence for their effectiveness in preventing influenza virus transmission either when worn by the infected person for source control or when worn by uninfected persons to reduce exposure." https://www.cdc.gov/eid/article/26/5/19-0994_article https://www.cdc.gov/eid/article/26/5/19-0994_article > Disposable medical masks (also known as surgical masks) are loose-fitting devices that were designed to be worn by medical personnel to protect accidental contamination of patient wounds, and to protect the wearer against splashes or sprays of bodily fluids (36). There is limited evidence for their effectiveness in preventing influenza virus transmission either when worn by the infected person for source control or when worn by uninfected persons to reduce exposure. Our systematic review found no significant effect of face masks on transmission of laboratory-confirmed influenza.