Companies large and small are vying for a piece of what they believe will be a lucrative market for verifying shot status.

More businesses are starting to require proof of vaccination, but there are some states that have outright banned them.

What counts as proof of immunization when there’s no global database to tell a fake apart from the real thing?

Nearly half of state legislatures have considered bans, but only GOP-led states seem likely to pass them.

Ethical questions have been raised over the fairness of demanding vaccination passports. Some venues want to see them, and some governors want to ban them.