Imagine an America divided into two classes: those who have recovered from infection with the coronavirus and presumably have some immunity to it; and those who are still vulnerable.

“It will be a frightening schism,” Dr. David Nabarro, a World Health Organization special envoy on Covid-19, predicted. “Those with antibodies will be able to travel and work, and the rest will be discriminated against.”…

As Americans stuck in lockdown see their immune neighbors resuming their lives and perhaps even taking the jobs they lost, it is not hard to imagine the enormous temptation to join them through self-infection, experts predicted. Younger citizens in particular will calculate that risking a serious illness may still be better than impoverishment and isolation.

“My daughter, who is a Harvard economist, keeps telling me her age group needs to have Covid-19 parties to develop immunity and keep the economy going,” said Dr. Michele Barry, who directs the Center for Innovation in Global Health at Stanford University.