By Nita Farahany / Special To The Washington Post

Since the coronavirus pandemic began, bioethicists have warned about the dangers of “immunity passports”: documents attesting that a person has contracted the coronavirus in the past and therefore might carry antibodies that make them immune.

The risk is that a system of passports would lead employers and others to discriminate against people who lack them; and that their value would produce perverse incentives (to contract the virus to get a job, for example). No such formal passport system has yet arisen. But the arrival of coronavirus vaccines under emergency authorization in Europe and the United States raise the issue anew.

Until a vaccine is fully approved and widely available, we should not — except in the rarest of cases — make participation in society depend on immunity status. And yet the vaccination cards that will be issued by the Centers for Disease Control and Prevention and other public health agencies worldwide will make enforcing that norm a challenge.

The cards are meant to help remind people to get their second shots of these vaccines (which all so far require two doses), to specify the vaccine manufacturer and to ensure that in an emergency, caregivers know that someone has received this treatment. These are laudable goals, but the cards could easily become de facto entry documents required for people to attend school, get a job, dine at a restaurant or patronize businesses. Employers might mandate that workers show coronavirus vaccine cards before they return to the office, and once vaccines are available for children, schools might require students to show these cards to attend. Tech companies are already scrambling to create apps that would include vaccine and coronavirus testing information, and a digital vaccine passport for travelers will soon be introduced by the International Air Transport Association, a major airline trade group.

Some discrimination based on vaccination or immunity could be justified in special cases. Nursing homes may reasonably want to hire immunized staff before other applicants, for instance. (Although the goal is to immunize health-care workers as quickly as possible, minimizing this problem.) But for a host of reasons, the secretary of health and human services (current and future) should discourage the use of vaccination cards or apps for virtually any purpose other than guiding individual medical care. A section of the Food, Drug and Cosmetic Act pertaining to the “authorization for medical products for use in emergencies” grants the health secretary the power to set the parameters for such use. Under my reading of the law, he or she could specify that schools, employers and businesses cannot refuse entry to individuals who have not obtained a coronavirus vaccine. The reasons include scientific uncertainty about whether vaccines prevent viral transmission, concerns about equity in vaccine distribution, and the importance of maintaining public trust in the creation and distribution of the vaccine. The president could buttress that prohibition by issuing a related executive order.

We should resist the seemingly intuitive rush to give preference to vaccinated people. First, relying on the shots to protect unvaccinated Americans may give people a false sense of security. A restaurant might advertise that all of its employees have vaccine cards, to encourage customers to start dining in again. But none of the clinical trials underway has proved that the vaccines fully prevent either infection of vaccinated subjects or their continued shedding of the virus (although they do largely prevent symptoms). So asymptomatic transmission remains a live danger. Some early results from the AstraZeneca and University of Oxford trials, as well as data submitted to the Food and Drug Administration by Moderna, suggest that these vaccines may substantially reduce viral spread. But until we have more robust data on transmission, we cannot yet ease up on social distancing, masking and other preventive measures.

Second, vaccine cards (and immunization apps) could turn into powerful weapons of exclusion and discrimination. The planned distribution of vaccines to various populations — first to health-care workers, nursing home residents, the elderly — is based on their likelihood of contracting the virus or of suffering severe disease. That’s logical. But many others who have endured the greatest economic impact of the pandemic — people without underlying conditions who may have lost their jobs, or can’t work because they are caring for children at home — will be quite far back in line. Making participation in school, work or leisure contingent on vaccination will further entrench the economic inequities of the pandemic. (If the government offers appropriate guidelines for operating businesses safely — and provides support to help them do so — many non-vaccinated people can do their jobs while mitigating risk.)

What’s more, minority populations that have been hardest hit by the pandemic — both physically and economically — are the least likely to find shortcuts in line, as better-connected people may. The National Academies of Sciences, Engineering and Medicine and the World Health Organization have made the case against colorblind vaccine distribution strategies, although it remains to be seen if states will take their advice. But there’s much work to be done to build confidence in the vaccine in minority communities: According to a Pew Research Center poll in late November, only 42 percent of Black Americans said they would take a vaccine once approved, compared with 61 percent of white Americans. It will hardly help if the vaccines are used as blunt tools of discrimination, with racially disparate effects.

Without doubt, many people want the vaccine as soon as they can possibly get it. But outside of a few settings — front-line health care and, perhaps, the military — people should not be required to take a vaccine that has been approved only for emergency use, and they should face no penalty for declining to do so.

The FDA’s fast-track approval process suggests confidence in a vaccine’s safety and efficacy, but it will still be a while before we have the full picture. Earlier this month, for example, two nurses in Britain suffered allergic reactions to the Pfizer vaccine that had not been reported in the clinical trials, leading to a recommendation against giving this shot to individuals with a history of significant allergic reactions. There are likely to be other reports of adverse effects. We should let the full regulatory approval process play out, and allow people to wait until it does, before committing to a vaccine. Conditioning societal participation on taking a vaccine that’s not fully vetted won’t help rebuild trust in science and the public health system; at a time when skepticism of experts runs high.

Letting people make high-stakes decisions based on vaccination status would create other risks, too: A black market in forged cards could emerge. And there would be powerful incentives for people to find ways to cheat the system to get the shot sooner. Such scenarios underscore why, for now, the health secretary ought to limit the use of vaccine cards to their intended purpose: to help remind people when their second shot is due.

As a participant in the Moderna Phase 3 vaccine clinical study (who is antibody positive), I believe strongly that vaccines will help quell the pandemic. When vaccines have fully cleared clinical trials and when their adoption has become routine, things may be different. After all, we discriminate based on other kinds of vaccinations all the time. Three months ago, I was asked to provide documentation of my daughter’s vaccinations so that she could attend kindergarten. And Duke University required that all of its employees, including me, have a flu vaccine to be on campus this fall. But where the coronavirus vaccine is concerned, such practices are a long way off; as they should be.

Nita Farahany is the Robinson O. Everett professor of law and philosophy and director of the Initiative for Science & Society at Duke University.