"The problem, in part, is that the protection offered by the pertussis vaccine wears off by the time you reach adulthood. Until recently, however, this was not a problem. Back in those halcyon days when we vaccinated our children, the disease was not bouncing around our population and so it was okay that adults did not get re-immunized. (That's the whole point of herd immunity: it's hard to get sick from people who aren't sick...Graph credit Jen Kirby, based on data from the CDC. Via The Dish.
"How responsible are these non-vaccinating parents for my pertussis? Very. A study recently published in the journal Pediatrics indicated that outbreaks of these antediluvian diseases clustered where parents filed non-medical exemptions – that is, where parents decided not to vaccinate their kids because of their personal beliefs. The study found that areas with high concentrations of conscientious objectors were 2.5 times more likely to have an outbreak of pertussis."