Polio can be found in afghanistan and syria and some cases in nigeria. Every other country is clear d/t polio vaccination. Herd immunity describes a type of immunity that occurs when the vaccination of a portion of the population provides protection to unprotected individuals. Some people get the needle but still not immunized. Some people cannot be immunized e. g. people who are allergic to eggs, immunosuppressed. Measles: vaccine effectiveness- 44 cases in 2001 (importation) Outbreaks of measles in alberta- people not vaccinating their children. Herd immunity is important; wthout it vaccines wouldn"t work so well; small pox was eradicated d/t herd immunity. How to make a vaccine: vaccination/ immunization strategies. The virulent parental virus attenuation live attenuated vaccine. Live - with an ability to replicate in host cells. It is not the strongest of the species that survives, not the most intelligent that survives. It is the one that is most adaptable to change charles darwin.