“Immunity passports could reinforce inequalities both within and between countries,” said Emilian Kavalski, a professor at the University of Nottingham’s campus in Ningbo, China.
Some countries have already taken steps in that direction.
In Britain, now outside the E.U., Foreign Secretary Dominic Raab said vaccine certificates are “under consideration” even as other British officials dismissed the idea. Israel recently launched digital vaccination certificates to allow access to gyms or restaurants.
Israel also agreed to trial a travel bubble with E.U. members Greece and Cyprus to open the door for vaccinated travelers. Meanwhile, Cyprus has also said it will begin in May to welcome vaccinated visitors from Britain.
The European Commission is expected to submit a proposal on how to bridge the divides with the bloc this month, which could lay out a joint plan for digital vaccination certificates that would work across the E.U. and potentially beyond.
Compromise proposals could include exceptions for individuals who have recovered from covid-19 or those who can provide a recent negative test result.
It is unclear what a digital vaccine certificate would look like. Personalized QR codes — used in Israel and difficult to forge — would be one possible option.
But finding common ground across the E.U. will not be easy. Vaccination rates vary widely. So does the political will to put the vaccinated in the fast lane for travel — with countries most dependent on tourism cash leading the way.
“Those who are vaccinated should have full freedom,” said Austria’s Chancellor Sebastian Kurz, who has joined Greece and Spain in support of vaccination documents.
“Some countries are very much preoccupied with now,” Greece’s tourism minister, Harry Theocharis, told the Financial Times last month, in an apparent reference of German and French hesitancy.
Tourism accounts for about 20 percent of Greece’s GDP, which declined by 10 percent last year.
“People will gradually realize that there is not much of an alternative,” Andreas Papatheodorou, a Greek tourism researcher, said. If no E.U.-wide solution can be found, Greece and other countries may opt for bilateral deals, he said.
German Chancellor Angela Merkel has signaled openness to study possible vaccination certificates later this year. But she has insisted treating vaccinated travelers preferentially now “isn’t on the agenda, given the low vaccination coverage at this point.”
French officials have made the same argument. They also appear worried about how a proposed pass would be received by the large number of vaccine skeptics in the country. Only around half the population was willing to get vaccinated when the rollout began two months ago.
French vaccine approval has recently inched upward. Some officials still fear a “vaccination passport” would risk undoing that progress.
Some groups — including members of ethnic minorities or pregnant women — would be disproportionately impacted, because covid vaccination rates among them are lower than in the general population, according to recent studies. Young people who are last in line to receive vaccines or older people with no smartphones would also be disadvantaged.
There is also still no scientific consensus on the extent to which vaccines reduce transmission of the virus, raising the possibility that vaccinated travelers may spread the virus even if they do not get sick themselves, said Melinda Mills, director of the Leverhulme Centre for Demographic Science at Oxford University.
President Biden said last week that there will be enough vaccines for all U.S. adults by May. The European Commission hopes to vaccinate 70 percent of the E.U.’s adult population by the end of the summer, which would still leave more than 100 million Europeans without immunization in late September.
“If you introduce this right away, you’d be excluding a huge group just on age-based discrimination,” Mills said of possible “vaccine passports,” adding that court challenges would probably follow.
Other questions are piling up, too.
Would E.U. citizens qualify for a certificate if they receive vaccines not approved by the E.U. drug regulator, such as Russia’s Sputnik V and Chinese vaccines? What happens if variants spread that reduce some vaccines’ efficacy?
Then there are privacy concerns. For decades, paper certificates have been used for travel to show vaccinations against yellow fever and other diseases.
But a digital certification, potentially with QR-codes, raises worries about whether the data could be used to track travelers’ movements.
Some global companies have already vowed to make use of their right to ban customers. Alan Joyce, the head of Australia’s carrier Qantas, said last year that proof of vaccination would soon become a prerequisite for flying.
“I think that's going to be a common thing, talking to my colleagues in other airlines around the globe,” he said. Similar requirements could be introduced for people entering sports stadiums or workplaces.
The idea of requiring travelers to carry health certificates is a relatively modern concept, said Kavalski, who has researched the historical evolution of passports.
Passports were widely introduced during World War I in what some saw as a temporary measure. But the 1918 flu pandemic helped shape international travel with “the practice of allowing only ‘healthy’ bodies to cross borders,” Kavalski said.
“I would say the [current] pandemic will have a lasting impact on the practices and experience of border crossing,” Kavalski said.