The plot depicts the spread of a contagious disease spread by vampirism (measles). Chloe Sevigny releases a terrible measles super virus upon the population when she releases the child of an anti-vaccination mother into the free world. A vampire measles breakout at a school turns the children against the superiors. I am pretty sure a lot of anti-vaxxers are murdered.
Read full story here: American Horror Story Slams Anti-Vaccination Parents