The number of students that were exempted from mandatory vaccinations last year is estimated to be 8,000. Washington County Public Health Director Danielle Pettit-Majeski says parents can get religious and medical waivers that exempt their children. She says what’s referred to as herd immunity is maintained if at least 90% of students are vaccinated, making contraction of a disease a student isn’t immune to less likely. If the percentage drops below 90%, it increases the chance of an epidemic starting among the children who are exempted.