One of the very first studies posted to the CDC website about mask efficacy, "Absence of Apparent Transmission of SARS-CoV-2 from Two Stylists After Exposure at

One of the very first studies posted to the CDC website about mask efficacy, "Absence of Apparent Transmission of SARS-CoV-2 from Two Stylists After Exposure at a Hair Salon with a Universal Face Covering Policy — Springfield, Missouri, May 2020," appeared to indicate masks were overwhelmingly effective. The success of this study has not been replicated to my knowledge. https://www.cdc.gov/mmwr/volumes/69/wr/mm6928e2.htm https://www.cdc.gov/mmwr/volumes/69/wr/mm6928e2.htm > Among 139 clients exposed to two symptomatic hair stylists with confirmed COVID-19 while both the stylists and the clients wore face masks, no symptomatic secondary cases were reported; among 67 clients tested for SARS-CoV-2, all test results were negative. Adherence to the community’s and company’s face-covering policy likely mitigated spread of SARS-CoV-2.