In May, nearly 140 people came in close contact with two hairstylists who were discovered, later, to have coronavirus.  The stylists wore masks, their clients work masks, and none of the guests at the Missouri  hair salon became ill, according to a report from the Centers for Disease Control and Prevention (CDC). 

From the report: 

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.

As stay-at-home orders are lifted, professional and social interactions in the community will present more opportunities for spread of SARS-CoV-2. Broader implementation of face covering policies could mitigate the spread of infection in the general population."

The report goes into further detail and can be accessed, in full, here.