Around the world, governments are looking for safe ways to lift unprecedented restrictions on public activities to curb the spread of Covid-19. So-called immunity passports could be key to the effort to selectively ease restrictions for people presumed to be immune to the virus. But there are scientific and ethical questions to be worked out before they can be deployed. .

As the world reels from the Covid-19 pandemic, two things have become very clear: the health impacts of the disease are devastating, but the aggressive social distancing policies currently being used to flatten the curve also have serious costs. As a result, the question of when and how to reopen the nation is on everyone’s mind. Do we open quickly in an effort to kick-start the economy? Or do we remain under lockdown as long as possible to stop the spread of the virus?

President Donald Trump had, until very recently, spent as much time in his public appearances proclaiming victory over the Covid-19 pandemic rippling across the nation as he had offering directives that would diminish it. Again and again, he promised that it would soon be over, especially as the wea...