What about the millions of other Americans who have already recovered from the virus? They are likely to have better immunity than a vaccine will confer, and we’ll all stop wearing masks once the population is properly vaccinated. It might seem logical to spare from the mask requirement those who’ve already recovered. We don’t because of two problems: identification and verification. Neither applies to the president.

If he walks into a meeting with no mask, everyone will recognize him. But if you walk into a store with no mask, people won’t know who you are. They’ll worry that you are a danger to them or conclude that it’s socially acceptable to drop precautions and endanger others. If Mr. Trump walks into a meeting with no mask after having recovered, everyone will know that he has been tested to verify he is immune and noninfectious. But if you return to work, who really knows if you’ve recovered?

If we act according to the science, President Trump won’t need to wear a mask in public. And if we understand human nature, you will.