@Kelly65 It isn't discrimination. Discrimination refers to something a person has no control over, that is part of who they are- the color of their skin, their age, their sexual orientation, a disability.
If the health decisions of guests mean that they could expose others to a deadly virus, that is very much a host's business. It has nothing to do with being nosy and hosts control all sorts of things about their rentals, from the number of guests they allow, to accepting pets or not, to where guests are allowed to park.
If people don't want to get vaxed, that's their prerogative, unfortunately, but it doesn't mean they are free to do whatever and go wherever they want and put others' health at risk. There are plenty of businesses that now refuse to allow the unvaxed to enter their place of business and proof of vaccination is going to be required to participate in many things and attend many events.
In case you aren't aware, vaccinations of all kinds are required for certain jobs, for the military, for school, to travel to certain countries, and have been for years. No one has ever called that discrimination.
Accepting the consequences of one's decisions is called being an adult.
You have the right to accept unvaxed guests just as other hosts have the right not to and for you to say the hosts who won't accept the unvaxed are in the wrong business is extremely rude.