@Michelle2137 Unless people decide to quit hosting altogether, the issue of breakthrough cases is one we just have to accept as a possibility.
But if the guests are vaccinated, the reports I'm reading now are that the vaccinated are less contagious, even if they have a breakthrough case, than the unvaxed. They shed less of a viral load. If the host is also vaccinated, that of course is an added protection. And while there have been breakthrough cases, the number of those compared to the number of people who've been vaxed is still relatively small.
I also think those who have been vaccinated would be more likely to let the host know if they think they might have contracted Covid anyway and are feeling ill, as well as taking more precautions re masking and distancing than the "it's just a little flu" crowd.