There is no such thing as herd immunity when it comes to pertussis, that is for sure.
It's amazing how much people miss, isn't Jan? I have a friend who has completely different parenting style than I do. Of those things, she vaccinates completely on CDC schedule. Her baby has been sick SOOO often - bronchitis, pneumonia (a very bad case of it, in fact), and other things as well. Coincidentally,... all these illnesses, she always came down with very shortly after routine vaccinations... hmmm. My friend didn't connect the dots, but I surely did!!
My 4 month old has only ever had one small cold. My husband got it first, he gave it to me, I gave it to baby. Baby was over before my husband was!! I truly believe he is so healthy because his immune system hasn't been damaged by vaccines, and of course because he's breastfed so was getting protection from me. All the people I know now that have never had vaccines are always healthier than those that have been vaccinated. It just seems so, "Duh!" considering they put immune suppressing toxins in the vaccines.