Yesterday evening, NPR ran a story on the recent judgment that the original study linking vaccination with autism was fraudulent. The charge is that the researcher in that initial study, Andrew Wakefield, falsified data to support the conclusion he wanted.
I posted the story to my wall on Facebook, and received several strident comments from an acquaintance who is convinced that vaccination is in fact harmful and that the new conclusions about the Wakefield study are themselves suspect.
Regardless of the merits of charge and counter-charge regarding the Wakefield, my exchange with this particular interlocutor soon turned to the question of whether the idea of "herd immunity" has any validity. My interlocutor asserted simply that there is "no evidence" to support the idea of herd immunity.