The most reputable source I could find that touches on pertussis vaccinations and disease spread is http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/uc..., particularly this part: This research suggests that although individuals immunized with an acellular pertussis vaccine may be protected from disease, they may still become infected with the bacteria without always getting sick and are able to spread infection to others, including young infants who are susceptible to pertussis disease.

The study, conducted on animals, does not, however, suggest that the vaccine increases rate of disease spread, rather that vaccinated individuals can serve as unaffected and unsuspecting nodes of transmission. This can happen with the acellular type of vaccine, not the whole-cell.

Here we go - it's another strain one can still be colonized by, not pertussis, but parapertussis: http://www.cidd.psu.edu/research/synopses/acellular-vaccine-... ("An acellular whooping cough vaccine actually enhances the colonization of Bordetella parapertussis in mice; pointing towards a rise in B. parapertussis incidence resulting from acellular vaccination, which may have contributed to the observed increase in whooping cough over the last decade.")

tl;dr: "We missed a spot." Which is going to happen. I don't think it validates being anti-every-vaccine, but it does validate asking questions and furthering research (and ceasing the vilification of the population that does ask questions!).

Without commenting either way on the veracity of the GP comment's claim, it sounds like you're asserting something on the basis of your own bias, here, too.

EDIT: particularly so, given the follow-ups to your comment's sibling, citing animal studies demonstrating exactly the thing claimed: that even vaccinated individuals can transmit the disease.