Handshaking for self-protection became anachronistic long before Dr. Anthony Fauci, the nation’s leading infectious-disease expert, said wistfully in early April that as far as even greeting one another, “we may never shake hands again.” As a personal defense mechanism and for sealing deals, though, it was outdated as soon as people began openly brandishing guns and hiring lawyers to vet contracts.

Habits are hard to break, however. We still hear “Bless you” in response to sneezes, although hardly anyone still believes Pope Gregory’s guidance that the expression would help ward off the plague. Also, this is not the first time in our history that an epidemic has weaponized a custom that originated as a means of assuring two strangers that neither was armed. After the 1793 yellow fever epidemic in Philadelphia, the publisher Matthew Carey wrote, “The old custom of shaking hands fell into such general disuse, that many shrank back with affright at even the offer of the hand.”