Where will the information come from? In the United States, there is no centralized federal vaccine database. Instead, the states collect that information. All states except New Hampshire have their own immunization registries and some cities, like New York, have their own. Currently states are required to share their registries with the Centers for Disease Control and Prevention, but the data is not public and could be withheld. That means anyone developing a digital vaccine certificate in the United States would have to obtain immunization data from individual states, which could be problematic in states that oppose health pass initiatives.