I have tried, and failed, to linkable find sources to back me up. They are not linkable as they are often news items in Swedish on local television, or in the spoken portion of reports to the local hospital board, but here is what I have got regarding Sweden:

• Omicron is, at least now and at least here, for practical purposes the only game in town. Latest waste water analyses discussed on local news was all Omicron.
  
• Spread was during the small delta wave here more among the unvaccinated (but that could also mean it was more among the young), however since November the spread numbers has been very similar among vaccinated and unvaccinated. If being unvaccinated is a random factor, you would get that result, but if it is correlated to various social factors, you would get heavier outbreaks among unvaccinated groups. And we haven't seen that.

Obviously if there are studies on the amount of virus exhaled among vaccinated and unvaccinated, that would settle the specific point.

However to be honest, unless there is a spectacular difference, I wouldn't change my mind on the passports. Because what we really need is to estimate the amount of virus in the indoor air, and in most pubs it will reach an unhealthy level even with just vaccinated, because most indoor places are not enough ventilated. Hence the yearly cold season.

Just to be clear, I think vaccinations are for most people a good thing to prevent serious illness and death. I got my covid booster shot friday and got my flu shot at the same time (the weekend was less fun). It is Covid passports I think is at best a wash, and potentially a bad public health policy. A massive air quality and ventilation program for public spaces (with heat exchange so save energy) would in my opinion be better.