To answer this question we’ll need to make a few assumptions including what percentage of the population needs to have immune system protection in order to achieve herd immunity, what percentage of the population will have been infected and recovered, and how effective the vaccines end up being on average.
Let’s assume that herd immunity is achieved when 75% of the population has immune protection, 15% of the population has been infected and recovered, and that the vaccine is 90% effective. If that’s the case, then we’d need to vaccinate about 4.7M of the 7.2M people that live in Arizona to get to herd immunity (15% of the 75% is achieved though natural infection and 60% via the vaccine). If the vaccines are on average 70% effective, then we’d need to vaccinate closer to about 5.7M Arizonans.
Our PowerPoint about the vaccines has a couple of slides explaining this idea.