Should we issue a “vaccination passport” or a “vaccination certificate” to people who have been vaccinated against the coronavirus? The debate is raging, especially in Europe, which is far from having decided on this contested measure. If ever the EU were to make this choice, how could such a document work? Difficult to say, but some countries, already more advanced on the issue, are exploring different solutions. Israel, for example, the most advanced country in terms of vaccination, is no longer very far from validating its “green passport”.