ARI SHAPIRO, HOST:
The World Health Organization is celebrating a major milestone in the global campaign to wipe out polio. Today it announced that a strain of the disease has been eradicated, but there has been a resurgence in cases of an unusual type of polio. NPR's Jason Beaubien reports.
JASON BEAUBIEN, BYLINE: In the incredibly ambitious multibillion dollar effort to wipe polio off the face of the planet, there's currently good news and bad news. The good news, says Michel Zaffran, who runs the World Health Organization's global polio eradication program, is that there's hardly any polio left.
MICHEL ZAFFRAN: When we started back in 1988, we had cases in 125 countries - 300,000 cases every year.
BEAUBIEN: Last year traditional polio crippled fewer than 100 kids and only in two countries - Pakistan and Afghanistan - and today the WHO declared one strain of the polio virus, called Type 3, eradicated. Type 2 was declared eradicated in 2015, so now there's only Type 1.
ZAFFRAN: So this is significant progress. It's slow progress, unfortunately, because we would like to have stopped all wild polio viruses, but it is a very significant accomplishment.
BEAUBIEN: But here's the bad news. The number of cases in Pakistan has gone from eight last year to 76 so far this year. And in Afghanistan, the Taliban last month did lift an all-out ban on polio vaccination but now will only allow the polio vaccine to be given in health centers. Zaffran says vaccination and clinics will never get immunization rates up to the 95% level needed to stop transmission of the virus.
ZAFFRAN: In Afghanistan, we've had only 19 cases so far this year, but we've accumulated a large number of unvaccinated children - pockets of unvaccinated children. So it's likely that there will be sort of many more cases before the end of the year.
BEAUBIEN: The other big problem facing the polio eradication program are ghost viruses linked primarily to the old Type 2 vaccine. The oral polio vaccine used in lower-income countries - and, I should note, not in the U.S. - is a live vaccine. Scientists have weakened the virus to the point that it will provoke an immune response without causing the actual disease. As billions of doses of vaccine were doled out around the world, some of that virus managed to get out into the environment, spread, mutate and regain strength. Now these vaccine-derived viruses are the primary source of polio outbreaks worldwide. There've been more cases of vaccine-derived polio globally this year than in any year other than 2009. Currently, there are 12 outbreaks in Africa. Last month another one was declared in the Philippines. Prior to that, the Philippines hadn't had a polio case since 1993. Vincent Racaniello, a virologist at Columbia University, says there are now more outbreaks of vaccine-derived polio globally than the actual disease.
VINCENT RACANIELLO: It actually is crazy because we're vaccinating now against the vaccine in most parts of the world - right? - not against wild polio, which is confined to Pakistan and Afghanistan.
BEAUBIEN: The WHO is well aware of this problem and has a long-term plan to switch to an injectable killed vaccine like the one used in the U.S., which protects against all three types of polio.
RACANIELLO: But that's turned out to be problematic because there was a production shortage up until not too long ago.
BEAUBIEN: Racaniello says the other tough problem is keeping up the funding and political will to vaccinate hundreds of millions of kids around the world against polio when there were only a few dozen cases each year. But he says the world shouldn't back off now.
RACANIELLO: I would just hate it if we gave up and then polio returned in big numbers. It would be so sad because it's totally preventable. And kids don't have to be paralyzed, at least not by polio, anymore.
BEAUBIEN: Jason Beaubien, NPR News.
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