The European Commission wants to issue a certificate, dubbed a Digital Green Pass, that would allow people who have been vaccinated to travel and move more freely. Commission President Ursula von der Leyen tweeted on Monday that "the Digital Green Pass should facilitate Europeans' lives. The aim is to gradually enable them to move safely in the European Union or abroad for work or tourism."

She said the plan would be rolled out later this month.

Southern European countries like Greece and Cyprus, whose economies rely heavily on the tourism sector, have been behind the push for such a certificate as they attempt to revive their battered tourism industries.

It's expected to take at least three months to set up a viable system, both technically and logistically. And that's where the problems start.

"Before vaccine certificates or passports are introduced, a large amount of the population would need to be vaccinated and a larger group of individuals would need to have access," Melinda Mills, director of the Leverhulme Center for Demographic Science at the University of Oxford, told DW via email. "For Europe, the current plans seem to be that around 70% [of the EU population] are to be vaccinated by the end of the summer." Currently, only 6% of the EU population has been vaccinated.

According to the Commission, the certificate's scope will go beyond documenting the vaccination status and include a person's broader medical history. "We will also be looking at other categories of information to avoid discrimination of citizens, such as test results and statements of recovery," Commission spokesman Christian Wigand said on Monday.

Ethical and privacy concerns

A main sticking point is expected to be the question of ethical standards and privacy issues. "A central ethical concern is to first determine who you would exclude if certificates were introduced. There are certain people who are unable to have vaccines for medical reasons such as those with allergies or pregnant women. In some countries, certain ethnic minorities are more vaccine hesitant, which would mean that this group could be inadvertently excluded," says Mills.

A report co-authored by Mills and published by the SET-C (Science in Emergencies Tasking: COVID-19) group at the Royal Society outlines a myriad of issues that need to be addressed before a viable system can be put in place.

One of the report's other lead authors, Chris Dye, professor of Epidemiology at Oxford's Department of Zoology, points out in the report that although some headway has been made on ethical, privacy and technical issues, there's a long way to go.

"Huge progress has been made in many of these areas but we are not yet in the best position to use vaccine passports. At the most basic level, we are still gathering data on exactly how effective each vaccine is in preventing infection and transmission and on how long the immunity will last," he wrote.

To avoid pitfalls and repeating past mistakes, the Commission would need to define and clarify the legal and ethical parameters of its usage, says Mills.

"A central ethical concern is to first determine who you would exclude if certificates were introduced. There are certain people who are unable to have vaccines for medical reasons, such as those with allergies or pregnant women. In some countries, certain ethnic minorities are more vaccine hesitant, which would mean that this group could be inadvertently excluded."

Other factors such as a differential roll-out across the EU or even something as mundane as digital access could exacerbate existing inequalities.

"Is it just something for international travel, medical uses, or is it broader, for getting a job, attending a football match or eating in a restaurant, buying some milk?" says Mills.

Then there are the legal ramifications. Vaccine passports will contain sensitive personal information so there must be clearly defined parameters such as purpose limitation and data minimization.

Protecting health data is a key component of the European Court of Human Rights (ECHR) mandate to protect the privacy of individuals but also to mitigate against disadvantages regarding a person's vaccine status such as age, ethnicity or gender. Legal data protection and privacy requirements need to be considered in relation to respect for private lives, which includes the protection of personal health information and biometric data.

What about discrimination?

This could open the next can of worms. Vaccination is voluntary — so what does that mean for those will those who don't want a jab or can't get vaccinated on medical grounds?

The ECHR recognizes the right to equality and guarantees against any type of discrimination. There is concern that vaccine passports could affect this protection if they structurally exclude a segment of the population. One of the arguments, also highlighted by the German Ethics Council, is that a vaccine pass could exacerbate structural disadvantages and lead to social stigmatization, especially in work environments.

"Some countries are looking into whether employers can take sanctions against those who are not vaccinated or whether it is their duty of care to protect their residents, customers and employers. There are also questions regarding which grounds people can legitimately refuse [a jab] ranging from medical reasons, religious but also political beliefs," says Mills.

While diligence and scrutiny are of the essence on this issue, the Commission is under pressure to expedite its plans, not least to shed its image of hesitant bureaucratic behemoth. In that respect, Europe could do worse than look to Israel, says Mills, who noted, "When the 'green passport' was introduced in Israel on February 21, access was granted across a wide range of age groups."