Given current, insufficient levels of protection, periodic measles epidemics are more or less to be expected. That’s because immunization rates appear to have plateaued, in recent years, at around 85 percent. Communities of vaccine skeptics, found in many different countries, contribute to this problem—but they’re not the only cause. They may not even be the major cause. In the U.S., for example, the number of unvaccinated children has quadrupled since 2001—a stat that people love to cite as evidence of a growing anti-vaxxer movement. But the CDC attributes that number to health care inequality, since kids without insurance or who live in rural areas appear to be at greatest risk.
The same applies to several of the countries where the latest measles crisis has been most devastating. Madagascar has registered more than 60,000 cases since January, but it’s not because people are refusing the vaccine; it’s because they can’t afford it.