pro-vaccinare http://www.nejm.org/doi/full/10.1056/NEJMsa0806477 pro-vaccinare geographic clusters concerned significantly raising the risk Approfondisci >> according to a study 2009 New England Journal of Medicine paper concerned concerned concerned Omer, Salmon, et al., 2009 http://www.nejm.org/doi/full/10.1056/NEJMsa0806477 http://www.nejm.org/doi/full/10.1056/NEJMsa0806477#t=article concerned concerned two percent saw their opt-out rates increase cuando se dejan de vacunar núcleos de la población their vulnerable neighbors concerned Approfondisci >> geographic clusters http://www.nejm.org/doi/full/10.1056/NEJMsa0806477 Approfondisci >> 35 times more likely An article in the New England Journal of Medicine http://www.nejm.org/doi/full/10.1056/NEJMsa0806477 since 1991 two percent minimum age requirements two percent quarter of all parents in certain communities reemerged about 2 percent refuse vaccines the rate