As states end their coronavirus restrictions, very few are creating systems to help businesses verify whether customers have been vaccinated against COVID-19.
Far more states are banning vaccine checks by public entities and, in some cases, also prohibiting businesses from denying service to those who aren't vaccinated.
Hawaii is the only state with some form of a vaccine passport for travelers.
California, Louisiana and New York have voluntary programs that let people download digital proof of vaccination that can be shown on smartphones or printed as QR codes for others to scan.
But many businesses are hesitant about asking customers for vaccine proof.