To be an anti-vaxxer you have to be stupid and gullible. Stupid in the sense of drawing bad conclusions from available information, and gullible in the sense of willing to believe bad information. I don't think I could come up with a better subgroup for scamming.
Though if I was in charge, I'd set up honey pots for these people. Get them to try to buy a fake vaccine pass, and then they never go home.