I personally know of five people to get the monoclonal treatment. One unvaccinated and four vaccinated.
We are running >100/month.
Usually we take them as they come so it would be rare to have two equally suitable patients, one vaccinated and one not, with only one dose to give.
However, I regard worsening COVID in an unvaccinated person as an emergency and will always suggest MAB for that person, while I'm more likely to wait it out in a vaccinated person.