This highlights a crucial point about vaccinations in general-herd immunity. Vaccinations are most effective when as many people get them as possible. When a community turns out in large numbers to get vaccinated, the treatment is more effective and everyone benefits, including those who opt out. In the U.S., about 92% of the population is vaccinated or immune and that makes it difficult for one case of measles to spread.
Outbreaks like the one at Disneyland could become more common as more families are choosing to forgo vaccinations, including the one for measles, mumps, and rubella. Although it has since been discredited and entirely rejected by the scientific community, a 1998 study suggested there was a link between autism and vaccinations. Still, some parents believe there is a causal relationship. Others fear too many vaccinations can harm a child's overall immune system.
Ultimately, there simply may be a communication gap when it comes to credible vaccination information. Last year in Ohio, there was a sizeable measles outbreak among the Amish community there. Medical professionals approached the community elders with information on vaccines and that seemed to do the trick, according to Dr. Robert Frenck, director of infections disease at Cincinnati Children's Hospital. He told The Wall Street Journal, "When the Ohio Department of Health went in and talked to their elders, they said we really don't have an objection to the vaccination. We just didn't understand it was that important."