Measles, misinformation, and risk: personal belief exemptions and the MMR vaccine

INTRODUCTION Across the United States, children entering schools are required to get a series of vaccinations that includes the measles, mumps, and rubella (MMR) vaccine.1 Designed to prevent those three devastating childhood illnesses, the MMR vaccine has proven highly effective and low risk. By the year 2000, decades of the vaccine’s use in the US led to the official elimination of measles in this country;2 during those decades, children had severe, vaccine-associated adverse reactions so infrequently that the Centers for Disease Control and Prevention (CDC) does not report them as causally linked.3 Nonetheless, a now-retracted 1998 paper linked the MMR vaccine with the development of autism. This paper set off the most-recent anti-vaccination movement—a wave of fear and mistrust of vaccines (and particularly of MMR) that persists in some communities to this day.4 Because of a clustering of such communities in affluent regionsofCalifornia,5 epidemiological conditions in the state became favorable for anew,