SANTIAGO, Chile — Government officials said Monday they would move ahead with plans to issue the world's first "immunity passports," cards that would allow people who have recovered from the novel coronavirus to return to work, over the concerns of physicians who warned that much about covid-19 immunity remains unknown.

Paula Daza, an undersecretary in the Chilean Health Ministry, said more than 4,600 people have recovered from the virus and will now be eligible to receive physical or digital cards. Holders will be exempt from quarantines and other restrictions.

Other applicants may be tested for the presence of antibodies to determine eligibility. Details have been sparse, but officials have promised a mass testing plan and say cards will be issued to people with a “very high probability” of being noncontagious.

“It’s precisely they who can help the community enormously, because they don’t present a risk,” Health Minister Jaime Mañalich said in announcing the cards last week.

But critics are warning against moving too quickly.

“There are serious doubts over the existence of long-term immunity to this virus, and there was no consultation with the Chilean Immunological Society before this measure was announced,” said Cristóbal Cuadrado, the technical secretary for health policy and studies with Chile’s medical union. “We have called upon the government to reevaluate the policy and involve experts in the discussion before implementing the scheme.”

Chile, which has tested more people than any other country in Latin America, has reported more than 10,500 cases of covid-19 and 139 deaths. President Sebastián Piñera last month declared a state of catastrophe; there’s now a nationwide curfew each night, quarantines in large sections of the capital and other regions, and highway checkpoints to restrict travel.

The government considers patients to no longer be contagious 14 days after acute symptoms have been registered or, in more serious cases, after they are discharged from the hospital. For those with weakened immune systems, it’s 28 days.

Scientists have questioned the reliability of antibody testing and the durability of immunity. South Korea’s center for disease control announced that 141 patients tested positive after they appeared to have recovered.

Chilean officials announced last week they would launch the card program on Monday. They have since delayed the rollout until later this week to allow final feasibility checks.

Piñera’s government has warned that the worst of the outbreak here is yet to come. The initial wave of cases is expected to peak in May; a second wave is possible in June. The approach of the Southern Hemisphere’s winter flu season is expected to further strain the country’s already overburdened health system.

Still, officials have pushed for a return to normality, sending government workers back to their offices Monday and easing some restrictions on movement.

The card program has brought additional concerns: That people who think they might be able to fight the virus would infect themselves to speed their return to work, or that a black market for the cards could develop.

Chile’s medical union says the initiative could lead to job discrimination, as employers give preference to cardholders.

The World Health Organization has kept its distance from the debate over immunity certification, but countries including Germany, Italy and Britain have considered the idea.

The United States has also weighed the idea, according to infectious-diseases chief Anthony S. Fauci, but he has urged caution about relying on antibody testing.

Rifat Atun, a professor of global health systems at Harvard University who has advised on health policy in Chile for more than 25 years, says the effort will yield important data.

“Testing for antibodies will give us valuable intelligence on the number of people who have been infected and where the hot spots are,” he said. “And with this information, policies and restrictions can then be introduced in a targeted, controlled manner.”

He added: “In terms of exit strategies, a game-changer would be a vaccine. But that may not come before the end of the year, even according to the most optimistic scenario. In the absence of approved treatments or a vaccine, measures that manage the pandemic may be the best we can do.”