"For somebody who's already been fully vaccinated, they can wear the mask out of solidarity or in a symbolic sense, but their
wearing a mask indoors is not benefiting anyone else," explained Vinay Prasad, an epidemiologist and biostatistician at the University of California, San Francisco (UCSF).
"There's an infinitesimally low probability of even having an infection that can be detected on a PCR test, let alone being able to spread it to someone," he added
Most indoor mask guidelines may be on way out in U.S., experts say