Italy considers screening residents for antibodies as it evaluates challenges of lifting lockdown.

ROME — There is a growing sense in Italy that the worst may have passed. The weeks of locking down the country, center of the world’s deadliest coronavirus outbreak, may be starting to pay off, as officials announced this past week that the numbers of new infections had plateaued.

That glimmer of hope has turned the conversation to the daunting challenge of when and how to reopen without setting off another cataclysmic wave of contagion. To do so, Italian health officials and some politicians have focused on an idea that might once have been relegated to the realm of dystopian novels and science fiction films.

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.

The debate about how to reopen arrived in earnest this past week in Italy. Like the virus’ crushing toll — some 15,362 dead in Italy as of Saturday evening — the shift is ahead of countries like Spain, Britain and the United States, where the contagion is still on an upswing.

Italy was the first European country to announce a nationwide lockdown, which it began March 9. But the rate of new infections slowed this past week — on Saturday, there were about 4,800 new cases, less than in recent weeks — leading officials and first responders alike to talk with guarded optimism.

“We are beginning to see the light at the end of the tunnel,” said Fabio Arrighini, a supervisor of an ambulance hotline in the Lombardy town of Brescia, which has one of the highest death rates in Italy. “The calls have gone down.”

Italy, by dint of its early and widespread exposure to the virus, has an opportunity to gain insight into how the virus works and the biological properties that protect against it.