Vaccine Passport Sandwich (to go)

I stopped in to pick up lunch at Mr. Subb today – I got a roast beef sub with Swiss cheese and Russian, if you’re curious – when I saw this sign. I’ve seen things like this on TV, but this is the first time I’ve seen a sign like this in person. I saw about four customers there. All were wearing masks. Were they all unvaccinated, or do they just lack faith in the vaccine’s efficacy? Or was it just a virtue signal? I thought about asking someone, but it’s such a touchy subject. No sense ruining my lunch with an argument, but it does make me wonder.