That's bayesian statistics for you. Measles vaccine works about 97% of the time. But if 91% of the population is vaccinated skewing the number of people who cat

That's bayesian statistics for you. Measles vaccine works about 97% of the time. But if 91% of the population is vaccinated skewing the number of people who catch the disease. P(H) - You have a 91% chance of being vaccinated. [2] P(H|P) - You have a 3% chance of catching measles if you are vaccinated and exposed. [3] P(H|P') - You have a 90% chance of catching measles if you are not-vaccinated and exposed. [3] P(H|D) - About 25% of the population that catches measles will be vaccinated. [4] (1) https://www.sciencenews.org/article/holes-herd-immunity-led-25-year-high-us-measles-cases https://www.sciencenews.org/article/holes-herd-immunity-led-... (2) https://www.fda.gov/consumers/consumer-updates/vaccination-best-protection-against-measles https://www.fda.gov/consumers/consumer-updates/vaccination-b... (3) https://www.nvic.org/vaccines-and-diseases/measles/measles-vaccine-effectiveness.aspx https://www.nvic.org/vaccines-and-diseases/measles/measles-v... (4) http://psych.fullerton.edu/mbirnbaum/bayes/BayesCalc.htm http://psych.fullerton.edu/mbirnbaum/bayes/BayesCalc.htm