There are (at least) two channels at play. Unvaxed people are more likely to spread Covid. Visible acceptance of anti-vax sentiment is more likely to attract more unvaxed people (and likely to reduce boosters among the ambivalent vaxed). When you’re not checking vax cards, you can adopt policies that make vaxx the default, obvious preference, even without formal enforcement.
There are (at least) two channels at play. Unvaxed people are more likely to spread Covid. Visible acceptance of anti-vax sentiment is more likely to attract more unvaxed people (and likely to reduce boosters among the ambivalent vaxed). When you’re not checking vax cards, you can adopt policies that make vaxx the default, obvious preference, even without formal enforcement.