DAVID GREENE, HOST:
So back in the year 2000, measles was declared officially eliminated from the United States after a full year of no transmissions. But now the Centers for Disease Control and Prevention is seeing a resurgence in the virus. New numbers were released yesterday, and so far 555 cases have been reported this year alone. So what should we understand about this spike? Let's turn to NPR global health correspondent Michaeleen Doucleff, who's been tracking this. Hi, Michaeleen.
MICHAELEEN DOUCLEFF, BYLINE: Good morning, David.
GREENE: So how bad is this outbreak?
DOUCLEFF: Yeah. So 555 cases is actually 50 percent more cases than we saw for the entire year last year. And we're only in April, so it's pretty significant. Another way to look at that is this is the largest - the second-largest outbreak we've seen in more than 20 years. And the CDC says that the numbers are only going to get worse, that it's accelerating.
GREENE: So far, I know we've been reporting that this is largely in New York. But is it popping up elsewhere?
DOUCLEFF: Yeah. So the vast majority of cases are linked to two in New York, one in Brooklyn and - one outbreak in Brooklyn and one in Rockland County, just north of the city. But the CDC also pointed to four other ongoing outbreaks in Washington state, Michigan, New Jersey and a few counties in California.
GREENE: So what happened? I mean, in 2000, it looked like there was no more measles. This was something - like, a virus that we weren't going to have to worry about anymore. What's going on?
DOUCLEFF: Yeah, so two things. Health officials say that two things are kind of coming together to really exacerbate the problem. First of all, measles is actually surging around the world right now. The World Health Organization just said that there have been four times as many cases worldwide this year than there were at this time last year. And several countries have massive outbreaks with tens of thousands of cases. That's like the Ukraine, Madagascar and the Philippines. But there's also significant outbreaks in several countries in the EU, Israel and a lot of parts of Southeast Asia. The CDC thinks that more families are traveling to these countries and bringing the virus back home.
And then, here at home, we have another problem. And that's vaccination rates. In several pockets around the country, communities' vaccination rates have dropped dramatically in the last few years below the level that's required to really protect the whole community. So once the virus comes to the U.S. from another country, it has a better chance of getting a foothold and triggering an outbreak.
GREENE: And this is a very contagious virus we should say - right? - compared to others?
DOUCLEFF: Oh, super, super contagious. So, like, it travels through the air. And if somebody coughs and sneezes on you, and you aren't protected with the vaccine, there's a 90 percent chance you're going to get infected.
GREENE: Which explains why we can see these numbers spike. You have a few people, parents who decide not to vaccinate, then, all of a sudden, I mean, it starts getting passed on in a significant way.
DOUCLEFF: Yeah, that's exactly right. And actually, communities need about 93, 95 percent of everyone vaccinated in order to really stop these outbreaks. And doctors say it's really important to make sure you have two doses of the vaccine, not just one. So parents should check to make sure everyone has two doses, including adults, in order to get full protection.
GREENE: Oh, that sounds like an important clarification. I mean, some people might think they've had a dose. They're vaccinated. But that doesn't do the job.
DOUCLEFF: Yeah. And it's important for adults to be vaccinated too. I know that I needed a booster, like when I was pregnant. So just make sure you check with your doctor that every kid and family member is vaccinated and especially with babies. Some doctors are recommending that if you're in an outbreak that babies get vaccinated early.
GREENE: NPR's global health correspondent Michaeleen Doucleff talking to us about this outbreak of the measles. Michaeleen, thank you.
DOUCLEFF: Thank you, David.
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