[Oliviaforever]

Recent piece on Herd Immunity.

http://www.washingtonpost.com/posteverything/wp/2015/02/03/why-a-few-unvaccinated-children-are-an-even-bigger-threat-than-you-think/

[trisham]

This might also be of interest:

http://scienceblogs.com/insolence/2008/08/27/mixing-unvaccinated-children-with-unvacc/