At a press conference following a meeting for the justice ministers of the European Union (EU) member states, Reynders said that since the US does not intend to issue a federal vaccination "passport," "we have to think about other kinds of proof for vaccination or recovery or tests, but it must be possible to solve the issue."
Reynders said the Commission was finalizing its new recommendations on free movement.
"I hope that this week we will make progress on new rules at EU level to lift the restrictions and to facilitate free movement," he said.
The EU's Digital COVID Certificate was proposed by the Commission to facilitate safe travel this summer. The system would allow the verification of national certificates in a secure and privacy-friendly way.
Available in digital format or on paper, it will provide proof that a person has been vaccinated against COVID-19, tested negative or recovered from an infection.
The regulation is scheduled to enter into force on July 1 with a phasing-in period of six weeks for any member state that needs additional time.