Reminder about Testing Accuracy in a population

Here a review of Bayes' Theorem and its application to remind us how estimations from small samples (even a million tests) are extremely inaccurate: 

P(A|B) = P(Covid|Test) = P(Test|Covid) * P(Covid) / P(Test) =
  0.99 * 0.01 / (P(Test|Covid)*P(Covid) + P(Test|~Covid)*P(~Covid)) =
  0.99 * 0.01 / (0.99*0.01 + 0.01*0.99) = 0.5

This question is on every MCAT exam but doctors forget it as soon as they begin practicing.