This post is not meant to convince someone not to vaccination, but rather to provide some insight into another reasoning why kids whose parents decide not to vaccinate should not be seen as a threat.
Also, vaccination may prevent the eradication of bacterial diseases. (Assuming that other factors are correct and that new sanitation can create the same effect as our so beloved Herd Immunity.)
Original antigenic sin, also known as the Hoskins effect, refers to the propensity of the body’s immune system to preferentially utilize immunological memory based on a previous infection when a second slightly different version of that foreign entity (e.g. a virus or bacterium) is encountered. This leaves the immune system “trapped” by the first response it has made to each antigen, and unable to mount potentially more effective responses during subsequent infections.
Vaccinated are 5-8 times more susceptible to asymptomatic infection. They can’t clear out the infection in the same way un-vaccinated people can.
Author: B. Damien. September 1998 Journal Medical Virology
Acellular pertussis vaccines protect against disease but fail to prevent infection and transmission in a nonhuman primate model. Jason M. Warfel, Lindsey I. Zimmerman, and Tod J. Merkel. vol. 111 no. 2 > Jason M. Warfel, 787–792, doi: 10.1073/pnas.1314688110. http://www.pnas.org/content/111/2/787.full
This makes the host immune to disease, but becomes a “carrier.” This is contradictory to Herd Immunity where it appears as though someone is immune, but they are actually carrying the pathogen.
This is something to keep in mind if you don’t vaccinate your kids. They can be exposed to pathogens this way. However, when it comes to being scared of un-vaccinated kids because they can spread the pathogen: at least you’ll know when they get sick.
Mandating vaccination (to go to school for example) is supposed to help eradicate diseases. But vaccination may be creating hosts that keep the pathogen in the community for a longer period of time.