I was in charge of the CDC. Here's my advice on verifying vaccines.

First, it needs to be accurate. Covid-19-specific vaccination data should be stored in and verified by a computerized immunization information system — essentially an online record of vaccinations people have received — that allows for sharing between systems. This approach is more accurate and would make it easier to verify vaccination status than a digitized version of a paper record. It may come to be the only version of verification accepted by international travel entities. Identity may need to be verified with a government-issued photo identification card such as a driver’s license.

Second, it needs to be secure and maintain privacy. Everyone should be able to control how her or his personal data is collected, stored and used. Safeguards must ensure that data will not be sold nor misused and that it will be used only for vaccination verification.

Third, there must be multiple options for people to retrieve and voluntarily present their vaccination status. People who don’t wish to or cannot participate in an electronic verification system should be able to use paper vaccination records with additional verification, such as a photo ID. Verifiers could then check this information against existing databases. Opting out, however, may also mean opting out of certain venues or activities that require digital proof of vaccination.