Chile plans controversial COVID-19 certificates.

Chile's contentious scheme to provide certification of past COVID-19 infection is aimed at reassuring patients about the risk of reinfection or infecting others. Barbara Fraser reports.

Chile is poised to become the first country to provide certificates to people who have recovered from COVID-19 to give patients confidence in the months following their illness. But some observers call the move premature, because of questions about whether the virus confers immunity—and if so, for how long—and about when a patient can be considered to have recovered.

“At this point, with the limitations about [rapid] tests, with the limitations about knowledge of [whether a person] who has antibodies is really protected, with the social problems that [could occur if people are still contagious], we cannot recommend this kind of measure”, said Jarbas Barbosa, assistant director of the Pan American Health Organization.

By May 4, Chile had confirmed 20 643 cases, nearly two-thirds of them in the area of Santiago, the capital, and 270 people had died.

The Chilean Government says that the “release certificate”—it backed off from calling it an “immunity passport”, a concept opposed by WHO—will enable people who have recovered from COVID-19 to “serve their community” with little likelihood of becoming reinfected or infecting others.

The certificate will not free the person from lockdowns in their neighbourhoods or of the obligation to wear a mask in public but is meant to provide some reassurance that they could help neighbours or elderly parents without much risk of infecting others or becoming infected, Chilean Health Minister Jaime Mañalich said.

“This pandemic is accompanied by great fear. The most violent feeling people have is [fear] that they will get sick and die”, Mañalich said. The certificate is a way of telling recovered patients “that the likelihood that they could become sick again or make others sick is extraordinarily remote—not non-existent, but extraordinarily low”.

In Chile, a person whose infection is diagnosed using RT-PCR, is considered recovered after 14 days in asymptomatic or mild cases or 28 days if the case is more severe or the person has a compromised immune system.

After 3 months, the certificate will expire and the person will be considered to have the same risk of infection as anyone else. Officials also hope the possibility of obtaining a certificate will encourage people who are diagnosed by private health-care providers to report positive results to the Health Ministry. Chile is basing its plan on data from Hong Kong and South Korea, Mañalich said.

But the evidence for immunity is inconclusive and many questions remain, said Daniel Altmann of the Department of Immunology and Inflammation at Imperial College London. Most antibody studies have involved hospitalised patients who had more serious disease, and whose immune response probably created a substantial amount of antibodies, “but that doesn't necessarily help you to understand the rest of the iceberg”.

A milder case “might mean they have made much less antibody, which might be why some of those people might be getting reinfected. We just don't know yet. It is a scary unknown”, said Altmann.

Barbosa warned that infection with most common coronaviruses results in only weak immunity, and Altmann noted that the few existing longitudinal studies of SARS and MERS indicate “dwindling immunity” by a few years after infection.

Chilean medical associations disagree with the idea of a certificate and “called for prudence” in light of WHO's position, said Cristóbal Cuadrado of the University of Chile School of Public Health, an adviser to the Colegio Médico.

The potential contribution to the community or the economy by the relatively small number of people who would qualify for certificates—about 10 000 as of May 3—does not justify the risk and uncertainty, or the possibility that the certificates could become grounds for discrimination, he said.

The Chilean Government declared a health emergency on Feb 8, nearly a month before the first case was detected on March 3, obtaining test kits and recruiting more health personnel, said Sebastián Peña, a Chilean doctor who is a visiting fellow at the Finnish Institute for Health and Welfare in Helsinki.

The government closed schools on March 25, reducing the movement of people in Santiago by about as much as lockdowns in other Latin American cities, said Peña. Instead of a national lockdown, health officials temporarily cordon off districts or sections of districts where outbreaks are detected.

Other countries have also considered some sort of certification for recovered patients with COVID-19 as a first step toward getting people back to work. But in an April 24 scientific brief, WHO stated that “there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an ‘immunity passport’ or ‘risk-free certificate’” and that a certificate could encourage people to “ignore public health advice”.