Measles outbreaks in the US typically start when a traveler picks up the virus in another country where measles is still common and brings it back to an unvaccinated community here.
In New York, the current outbreaks also originated with travelers who had recently visited Israel, where a massive measles epidemic is currently underway. The travelers returned to the US and spread it among unvaccinated or undervaccinated communities in New York state.
In the Washington outbreak, “patient zero” was also visiting from outside the country, carrying a strain of the virus that’s circulating in Eastern Europe, and came into contact with unvaccinated children in Clark County. Those children then visited public places including health care facilities, schools, and churches, as well as Ikea and Dollar Tree, spreading measles to others.
What these two outbreaks have in common: They’ve both happened in communities with high rates of people who opted out of vaccines on behalf of their children, making them more susceptible to entirely preventable diseases. And in both states, the outbreaks centered on tight-knit, traditional communities (in New York, ultra-Orthodox Jewish communities, and in Washington, Slavic immigrants).
These communities have become an urgent focus of health departments across the country, said Nancy Messonnier, the director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention. Before New York and Washington, it was vaccine-refusing Amish in Ohio and Somali Americans in Minnesota. When measles strikes, outbreaks in tight-knit groups tend to be “explosive” and more difficult to control.
While all 50 states have legislation requiring vaccines for students, almost every state allows religious exemptions to immunizations, and 17 states grant philosophical exemptions for those opposed to vaccines because of personal or moral beliefs. (The exceptions are Mississippi, California, and West Virginia, which have the strictest vaccine laws in the nation, allowing no philosophical or religious exemptions.)
Oregon and Washington are among the 17 states in the US that allow philosophical vaccine exemptions. In 12 of these states, the rate of these exemptions has risen since 2009.