Questions in picture

9. Herd Immunity Suppose we have a measles outbreak in a small community of 40,000 people, almost all of them Susceptible, with b = 1/(14 days) and a = 0.000003. a) What is the threshold in this problem? How many people will get sick before the epidemic reaches its peak? b) Now suppose that 10,000 people (out of 40,000 total) are immune to measles, either because they already had the disease or because they were vaccinated. How many will get sick before the epidemic reaches its peak? c) If enough people are immunized, the epidemic will fizzle from the start. How many people would have to be immunized for that to happen? d) When enough people are immunized to keep outbreaks from spreading, the population is said to have herd immunity. Explain how the number of vaccinations needed for herd immunity is related to the threshold b/a. e) If you were a public health official, what would you say to somebody who doesn't want to get vaccinated and who insists that their (not) getting vaccinated is none of your business