“Interestingly, the CDC’s Pertussis Frequently Asked Questions page says this (emphasis mine):

Even though children who haven’t received DTaP vaccines are at least 8 times more likely to get pertussis than children who received all 5 recommended doses of DTaP, they are not the driving force behind the large scale outbreaks or epidemics.”

Read more: http://www.naturalblaze.com/2015/03/the-truth-about-recent-pertussis.html#sthash.TVLiHmBY.dpuf