Lesson 3 Herd Immunity

Definition: The amount of people that have immunity in a population. A specific level of immunity must be reached for the weakening of the disease to take place.

Immunity among the majority of the population can decrease the risk of contracting the disease for vulnerable individuals

High vaccination levels may mean that the chance of being infected is close to 0


  • Successful immunization programmes still have a low level of risk of causing you severe side effects or catching the disease with severe symptoms.
  • The risk of getting the disease is lower due to the protection that the vaccine gives you


  • Vaccination helped in the elimination of various common childhood contaminations
  • Late 1970’s -Global eradication of smallpox