But Healthvana also says its records create a verifiable proof of vaccination. That proof, sometimes discussed as a “vaccine passport,” could allow safer protocols for public gatherings or other settings where transmission risk is high as the vaccine becomes more widely available.

In Los Angeles, where the spread of the novel coronavirus has reached crisis levels, the Healthvana records will supplement paper reminder cards given to recipients of a first vaccine dose. Though vaccine records are also kept by medical facilities, county officials tell Bloomberg that medical administrators don’t have the capacity to track the timing of millions of necessary follow-up doses and inform patients directly.

That matters because the two COVID-19 vaccines currently approved for emergency use in the U.S. are only fully effective after a second dose. Studies based on other multi-dose vaccines show that a large proportion of patients, particularly the elderly, disabled, and members of minority groups, do not return for a second dose. That could slow the progress to the vaccination threshold of roughly 80% that health authorities say is needed to control the pandemic in the U.S.

The Healthvana system also creates proof of a completed vaccination sequence that can be stored digitally in an Apple Wallet or similar systems. Those systems already provide authenticated and secure storage of official records such as student IDs, airline boarding passes, and event tickets.

Secure digital vaccine records could in theory be used to safely allow access to places or activities, such as airlines or public events, where there is a high risk of coronavirus transmission. Healthvana says it is in discussions with such facilities about using its certifications for that purpose. However, there is currently no official state or national U.S. policy—or broad private-sector consensus—about how such a system might work.