Public health experts and bioethicists say digital credentialing could discriminate against disadvantaged populations. The Electronic Frontier Foundation, a digital rights group, argues that using smartphone-based verification to access public places would create a two-tiered system that bars people who can’t work, shop or attend school because they don’t have a cell phone or access to testing…

Data troves containing immunization records vary in quality from state to state and may not be able to handle a surge of real-time queries about vaccination status, said Deanne Kasim, executive director at Change Healthcare, which is part of a consortium including Microsoft and Salesforce working on standards and technology for passports. Her company argues for a “lighter lift” and teaming up with pharmacies, which have more robust record-keeping systems.

There also are privacy considerations. Requiring people to store test and vaccination results in digital format could expose them to the kind of data breaches that have proliferated during the pandemic. “We wanted data to reside on patients’ phone” as opposed to a database, where individuals can control the data, Kasim said.