Future Tense

Can Vaccine Passports Actually Work?

A hand holds a smartphone screen showing a vaccine passport, in front of the New York City skyline.
Chris Delmas/AFP via Getty Images

This article is part of Privacy in the Pandemic, a Future Tense series.

This summer, Martina and James are getting married. The invitations have been sent to family and friends, but only those with a Green Pass—the digital vaccine passport system that recently became active in Italy—are allowed to join the festivities in a picturesque town on the coast of the Ligurian Sea. No exceptions, not even for the bride and the groom.

The wedding was canceled last summer when Italy was fighting the first outbreak of COVID-19. This time, a digital vaccine passport might allow the two to share the big day with their loved ones (at least those who pass the health screening). But will it also keep them safe from COVID-19? How about the risk of surveillance, health stigma, and discrimination?

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Once again, technology promises us a way out of the pandemic, the respect of our privacy, and the ability to control our health choices. But as more jurisdictions are experimenting with this new technology, we are getting a clearer picture: Digital vaccine passports cannot have it all. Unless governments have the courage to set clear priorities for its use, vaccine passports will follow the same trajectory of digital contact tracing: from stardom to complete irrelevance in only a few months.

COVID-19 passports are digital systems that provide proof that their holder constitutes a low risk to public health. In most cases, they allow the holder to present either a certificate of inoculation or a negative COVID-19 test from the preceding 24–72 hours. Some countries also accept a certificate of recent recovery from infection. Verification of identity connects the pass holder to the health information.

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Most systems share information through QR codes generated by health care providers. At the door, the venue host will scan the QR codes that Martina, James, and their digital-savvy wedding guests have uploaded on a smartphone app, or printouts for the low-techies. If the QR code shows the guest satisfies the applicable health requirements, she will join the reception. If not, she’ll stay out.

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While the system seems simple, it requires a great deal of coordination between the many health care providers who subminister vaccinations or COVID-19 tests and an even larger amount of information receivers—the venues that validate the QR code. The vaccine passport on a smartphone is a mere intermediary between the two.

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Once the system crosses countries’ borders, the need for coordination escalates. For Martina and James to attend their own wedding, for instance, the digital credentials issued by health care providers in the U.K., where the couple lives, need to communicate with the Italian system (in what is technically called interoperability). If vaccine passports are to be interoperable at a global scale, health care systems across the world must generate digital credentials in a format that apps in any country can read and decode as a pass.

We are far from that goal. The European Union has set standards to ensure that national vaccination credentials are interoperable and the underlying data on vaccination and test results are harmonized across member states. Outside of the EU, however—even though the World Health Organization has proposed guidelines—that data ecosystem can be far more fragmented.

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In the U.S., vaccination data are distributed over 60 different databases that are not designed to easily share data, according to Paul Baier, interim president at PathCheck Foundation, a nonprofit dedicated to creating technology to fight the pandemic. “To overcome this cost challenge, some states are considering a $5 charge for a government-validated covid vaccination card. Bermuda is considering charging 75 cents,” he wrote in his newsletter on June 17.

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In most locations, efforts to provide digital vaccination credentials have been fractured by industry and geography. For example, systems like AOKpass have been adopted by airlines to reopen international travel. Israel’s Green Pass and New York’s Excelsior app, on the other hand, are meant for local use.

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The Excelsior Pass, for instance, might not be considered valid proof of vaccination for U.S. guests at the Italian wedding venue (or, as a matter of fact, outside of New York). If New York’s vaccination credentials are not harmonized with the European system, those coming from across the Atlantic might not even be able to record their health status via the Italian Green Pass (or any U.S.-based digital vaccination, if they have different technical specifications). However, they would be able to show an alternative certificate like a validated vaccination card.

You might be wondering: Wait, if I can just show a vaccination card, why would I ever need an app? This is where the issue of privacy comes in. Vaccine passports might represent the least restrictive option to quickly reopen while preserving the right to conduct a private life, according to a report of the Ada Lovelace Institute.

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Suppose you have not been jabbed. At the wedding venue, you might show a negative COVID test. The lady next to you in line peeks at your papers, rolls her eyes, and whispers to her date, “Another one of those people who just won’t get vaccinated.” If you present a medical certificate of recent recovery from COVID-19, she might take a step back for an extra foot of protection. Suppose that happens every time you visit your hairdresser, enter a bar, or go grocery shopping.

To overcome that risk, most systems launched so far show whether the holder complies with the requirements for access but hide what generates the pass: a vaccination, a negative test, or a certificate of recent recovery. Paper-based health records would be unable to achieve the same goal.

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That can solve the potential for social stigma but creates a new privacy threat: that of tracking. By validating the pass at every location visited, vaccine passports create a digital ecosystem of data on one’s health status and whereabouts—two salient pieces of one’s identity that could be damaging when in the wrong hands.

In response to concerns over data breaches and tracking, IBM designed a digital vaccination passport system based on blockchain technology, where individual information is never collected into a centralized dataset but remains stored on the individual device and gets exchanged via data networks. IBM ensures that its Health Pass gives the owner full control over when and where to share her data.

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In theory, this system meets the minimum criteria petitioned by the American Civil Liberties Union for digital vaccine passports: a hybrid digital and analogical system that is decentralized, based on open-source specifications, and user-centric without the creation of a large repository of sensitive information.* Despite that, concerns over civil liberties remain. The Biden administration has ruled out federal use of vaccine passports, and a new bill was recently introduced in Congress and the Senate to forbid federal support of third parties, such as airlines, in implementing these systems.

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States can still pursue them, though many have banned their use. New York launched one in early April. More than 2 million Excelsior Passes have been downloaded so far. Uptake of the pass is completely voluntary for both public and private venues. They can decide whether to require visitors to show their passes upon entry. Some sports and performance venues have already done that, and your upstairs neighbor might elect to do the same at his next potluck dinner.

On the other side of the Atlantic, implementation rules have been stricter. Denmark, where the first EU-based app was launched in April, made its Coronapass mandatory to enter certain businesses, like hairdressers and tattoo parlors, cinemas, theaters, and gyms, with fines for noncompliers.

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The Danish system enjoys high levels of support. A vast network of testing centers in the country preserves the mobility of those who lack immunity. But where testing is costly or time-consuming, vaccine passports can amount to an immunization requirement even if legal COVID-19 vaccination mandates have been a contentious topic.

In most countries, including the U.S., COVID-19 vaccines are approved under an emergency use authorization, a rigorous but less extensive review of their effects. Concerns over limiting individual liberties and fueling anti-vaxxer movements have demoted the measure to the last resort.

In absence of legal requirements, Israel tried with incentives. Its Green Pass system was designed to encourage vaccination uptake. It allowed access to social, cultural, and sports events and locations such as gyms, hotels, and restaurants to those who had recovered from COVID-19 or were fully vaccinated. A negative test was not an acceptable credential.

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The country now enjoys one the highest vaccination rates in the world and recently ditched the mandate to use its Green Pass after the infection rate dropped significantly, an example of setting time bounds to the use of these technologies. The accomplishments were celebrated as the country’s official defeat of COVID-19 and a win for advocates of vaccination credential systems.

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Yet the Ada Lovelace Institute suggests caution. A vaccination passport that introduces mandatory immunization by the back door might deepen the distrust in vaccination efforts to begin with, especially among marginalized groups who, in many countries, already have lower rates of vaccine uptake.

But Israel’s strategy might be the most sensible use of vaccination passports, at least for now. The vaccines currently available avert the onset of harsh COVID-19 symptoms and in many cases hospitalization, but whether they prevent the spread of its underlying virus—SARS-CoV-2—is still an open question.

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Though recent studies point in that direction, we’re short of conclusive evidence that vaccines substantially reduce transmission—and digital vaccination schemes that accept negative test results might create a system that protects people’s privacy but does not prevent contagion. Most at risk are the unvaccinated, who are unprotected while sharing spaces with potential carriers. The risk would be greater if a misguided feeling of safety gets people to let down their guard on other preventive measures whose effectiveness is well established by now, like wearing masks or social distancing.

Yet, the promise of bringing back a normal life fuels extraordinary support for these schemes. More than 66 percent of Americans approve of digital vaccine passports to reopen the domestic economy, according to a survey from the Institute for Technology and Global Health. These numbers are comparable to the 67 percent approval rate in Denmark. Across international borders, on average 78 percent of the global population supports vaccine passports for international travel even if vaccine access is unequal across countries.

The Coronapass “makes you feel safer,” a Danish interviewee told the BBC. It’s still not clear whether vaccine passports actually make us safe or if it is just security theater to get people out of their homes and into an economy that cannot sustain another summer of inactivity. But at the wedding, I hope everyone still remembers the three W’s: Wear a mask, wait 6 feet apart, and wash your hands.

Correction, July 15, 2021: This article originally misstated that IBM’s vaccine passport system is open source. It is based on open-source principles.

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.

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