We are hosts with a room in our home to share with Airbnbers. Both my husband and I have been vaccinated and state that and also include, "and hope you will be, too". Today I received a request from someone from France asking if we only accept those who have been vaccinated. Trying to make certain it is legal to deny the request because someone is unvaccinated.
Don't know the rules in your country, but in my country travellers from France need to do 10 days quarantaine, as France is still regarding COVID at risk.
But you can also reply to the guest you prefer vaccinated guests and ask the guest to retract the booking (so it saves you to make a decline).