If my children are fully vaccinated, what are the chances they can get one of those illnesses?

I live in Florida where rising levels of suspicion of medical professionals is leading to an outbreak of (currently) measles and, in some areas, a sharp decline in vaccination rates. Our senate just passed a bill that allows essentially anything to be a vaccination exemption, which essentially guts protections kids would typically have at public school, daycares, etc.

My kids are fully vaccinated, and we stay on top of their seasonal vaccines. Our pediatrician has a blanket no exemption policy for their clients, else you're invited to go to another practice. However, my children do/will attend public schools, and likely soon now with unvaccinated children. What is the risk of them catching a disease when they're fully vaccinated, but the vax rate falls to, say, 80%? Aside from the obvious (moving, homeschooling), what are some options we as parents have to safeguard our kids?