While the United States government has not issued a federal digital vaccine pass, a national standard has nevertheless emerged. To date, 21 states, the District of Columbia and Puerto Rico offer accessibility to the SMART Health Card, a verifiable digital proof of vaccination developed through the Vaccination Credential Initiative (VCI), a global coalition of public and private stakeholders including Microsoft, Salesforce, Oracle, the Mayo Clinic and other health and tech heavyweights.

And very soon, at least four more states will be rolling out access to SMART Health Cards. "We've seen a notable uptick in states that have officially launched public portals where individuals can get verifiable vaccination credentials in the form of SMART Health Cards with a QR code," says Dr. Brian Anderson, co-founder of the VCI and chief digital health physician at MITRE.