The European Union on Wednesday launched a closely watched effort to create a joint vaccination passport for its more than 440 million citizens and residents, embarking on a tightrope walk between economic pressures, discrimination fears and concerns over Europe’s slow vaccination progress.

Supporters hope the “digital green certificates” will be ready by June, which could help to salvage the European summer tourism season and even serve as a model that could be extended to the United States and other countries. But E.U. countries lag far behind the United States in vaccinations, which has raised concerns that the passport plan could be launched prematurely.

The passes are expected to be digital or paper documents for travelers to prove that they have been vaccinated, that they recovered from the virus or recently tested negative for it. In many cases, this could free travelers from quarantine obligations.

An easing of those restrictions remains unlikely in the short run, amid persistent E.U. concerns over new coronavirus variants. President Biden also reimposed an entry ban on most European travelers in January, which could become another obstacle, as E.U. officials have cited reciprocity as a factor in their decision-making on travel restrictions.