Bill Gates announced digital vaccine passports during a March 2020 TED Talk interview.
Eventually what we’ll have to have is certificates of who’s a recovered person, who’s a vaccinated person” and “so eventually there will be this digital immunity proof that will help facilitate the global reopening up.”

This sentence on "digital immunity proof" was edited out by the TED Talk producers, but the sentence remained in a full audio version of the interview.

Such ‘vaccine passports’ are a key component of the biometric ID2020 project (https://www.biometricupdate.com/201909/id2020-and-partners-launch-program-to-provide-digital-id-with-vaccines