http://www.cdc.gov/measles/hcp/ http://www.cdc.gov/measles/hcp/ >One dose of MMR vaccine is approximately 93% effective at preventing measles; two doses are app

http://www.cdc.gov/measles/hcp/ http://www.cdc.gov/measles/hcp/ >One dose of MMR vaccine is approximately 93% effective at preventing measles; two doses are approximately 97% effective. Vaccination does not confer effective immunity in all those vaccinated. If an outbreak hits a school or day care, the 4 day period in which the infection is contagious before any symptoms appear means that most of the kids will be exposed, and any who are not immunized (either not vaccinated, or vaccination was not effective) are at risk. I view those who choose not to vaccinate children who could be vaccinated as freeloaders, depending on the rest of us to provide group immunity to protect their children. For those for whom it is a personal preference or belief, rather than part of a religious practice, I wish they would choose to accept their share of the risks.