In Denmark, a law was recently enacted allowing (not requiring) employers to demand a "coronapas" (health passport). Many of the largest municipalities have availed themselves of this possibility (including my employer).

You have a valid coronapas if you've been vaccinated, had a negative PCR test in the last 72 hours, or had a negative antigene test in the last 48 hours, or have recovered from covid in the last 6 months.

The obvious problem (and the reason why cases are exploding) is that vaccinated people are spreading the virus because most don't bother to get tested (why should they? People were told that the vaccine would defeat the pandemic and many still believe this). Unvaccinated, otoh, are getting regularly tested and must self-isolate if they test positive.

Mass vaccination against an airborne virus is not the best way to defeat the pandemic. Regular testing and effective contact tracing is.

Vaccination should have been reserved for the high-risk groups (although even triple-vaccinated elderly people are dying, as are those with comorbidities).