Vaccines by themselves are not 100% effective (see the Measles outbreak from earlier this year [1]). The additional benefit of Herd Immunity[2] helps to increas

Vaccines by themselves are not 100% effective (see the Measles outbreak from earlier this year [1]). The additional benefit of Herd Immunity[2] helps to increase the effectiveness, which is at risk of being lost the more the anti-vax movement gains traction. 1: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm 2: http://www.niaid.nih.gov/topics/pages/communityimmunity.aspx http://www.niaid.nih.gov/topics/pages/communityimmunity.aspx