Why? Because people have learned not trust them

TIME, March 5, 2020: Why people aren't listening to experts about face masks

Face masks are in short supply—despite the CDC specifically not recommending them for healthy people trying to protect against COVID-19. “It seems kind of intuitively obvious that if you put something—whether it’s a scarf or a mask—in front of your nose and mouth, that will filter out some of these viruses that are floating around out there,” says Dr. William Schaffner, professor of medicine in the division of infectious diseases at Vanderbilt University. The only problem: that’s not effective against respiratory illnesses like the flu and COVID-19. If it were, “the CDC would have recommended it years ago,” he says. “It doesn’t, because it makes science-based recommendations.”

The science, according to the CDC, says that surgical masks won’t stop the wearer from inhaling small airborne particles, which can cause infection.

That was last year’s perceived wisdom; it will be interesting to see what “science” has to say next year about vaccines.