Measles, once a common childhood infection that killed up to 500 Americans a year, has been officially eradicated in the Western Hemisphere. For many years, the USA's few dozen measles diagnoses were "imported" cases in individuals who traveled from countries where the virus remains common. High vaccination rates largely halted the virus at the North American border.
The country's safety net has become more porous in recent years. Although overall vaccination rates remain high, communities of like-minded parents who refuse immunizations for their children have been vulnerable to outbreaks.
Bob Garfield of NPR's On the Media program said it well last month in a piece about ABC's The View hiring anti-vaccination advocate Jenny McCarthy:
Thanks to McCarthy's huge media profile, untold numbers of mothers have foregone the measles-mumps-rubella vaccine, and others, for their children, with potentially catastrophic public health consequences. Outbreaks of measles and pertussis in the US over the past five years, after decades of virtual eradication, underline the stakes.