Having the right antibodies to the virus in one’s blood — a potential marker of immunity — may soon determine who gets to work and who does not, who is locked down and who is free.

That debate is in some ways ahead of the science. Researchers are uncertain, if hopeful, that antibodies in fact indicate immunity. But that has not stopped politicians from grasping at the idea as they come under increasing pressure to open economies and avoid inducing a widespread economic depression.

The conservative president of the northeastern Veneto region has proposed a special “license” for Italians who possess antibodies that show they have had, and beaten, the virus. The former prime minister, Matteo Renzi, a liberal, has spoken about a “Covid Pass” for the uninfected. Prime Minister Giuseppe Conte said that while the lockdown remained in place, the government had begun working with scientists to determine how to send people who have recuperated back to work.