When we originally ran this episode, Flu season was at its worst, and an old illness considered

long gone, measles, was suddenly making a comeback. The root of the problem was a fight over whether

people can opt out of vaccination if that means jeopardizing the greater public's health.

It's that season again, and the fight continues. So we're offering another look at the history

of anti-vaccination debates in the US.

Tonight, America on track for its worst measles outbreak in 25 years.

CDC says the number of measles cases being reported is close to the danger zone.

This orthodox Jewish section of Williamsburg, Brooklyn, is ground zero, where some 250

measles cases in just one week. 71 students, 127 staff.

The latest outbreaks are highlighting pockets of unvaccinated people, and how the

officials are scrambling to stop the nationwide spread.

You're listening to Thru Line from NPR, where we go back in time to understand the present.

Back in 2000, the Centers for Disease Control and Prevention, or CDC, officially declared that

measles had been eliminated. But now, according to the CDC, we're in the midst of the biggest

outbreak of measles since that declaration. So what's going on?

Well, public health officials have linked many of the recent outbreaks to people who have

become infected while traveling abroad. But the question is, why has the infection been

able to spread so widely, especially among American children?

I do believe that parents' concerns about vaccine leads to under-vaccination,

and most of the cases that we're seeing are in unvaccinated communities.

However, that's a CDC official testifying before Congress in February.

And basically, what she's saying is that people weren't getting their kids vaccinated,

...