When the coronavirus began spreading, officials seemed to be promoting two contradictory ideas: First, masks would not help keep people safe; and second, masks were so important that they should be reserved for doctors and nurses. It reminded me of the line credited to Yogi Berra about a New York restaurant: “Nobody goes there anymore — it’s too crowded.”

The truth has become clearer in recent days. Masks probably do provide some protection. They’re particularly effective at keeping somebody who already has the virus from spreading it to others, and they may also make the mask’s wearer less likely to get sick. “Coronavirus appears to mostly spread when germ-containing droplets make it into a person’s mouth, nose, or eyes,” Vox’s German Lopez explains. “If you have a physical barrier in front of your mouth and nose, that’s simply less likely to happen.”…

True, public health officials were in a difficult position. Masks are indeed more important for doctors, nurses and other front line health workers than for everyone else. Health care workers are at far greater risk of being exposed not only to the virus but also to dangerous levels of it. And if they do get sick, they could spread the virus further — and would be unavailable to treat others.