Where did polio and whooping cough go? Why have they returned?
Why are you even on Freerepublic? You hate the thought of families making informed decisions based on research and freedom!
Polio gets reintroduced by immigration, it has a fecal-oral vector. You would need to come in contact with fecal matter and ingest it. Like swimming in a lake where lots of infected people have been. Or changing the diaper of a baby that received the live vaccine
Pertussis vaccine is a vaccine against the toxins the bacteria produce. They don't kill the bacteria. By having antibodies to the toxins your body is able to destroy the toxins before they help the bacteria get a full blown infection going. So the bacteria are around just can't get a colony going in enough numbers to let you infect somebody.