The Next Stage in the War on Polio

The oral vaccination used in the world's largest global health campaign, a successor to that first developed by Dr. Hilary Koprowski, who passed away this past weekend, comes with its own set of risks.
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The oral vaccination used in the world's largest global health campaign, a successor to that first developed by Dr. Hilary Koprowski, who passed away this past weekend, comes with its own set of risks.


Before it all started, in the early summer of 1950, there was a persistent promise of prosperity in Wytheville, Virginia. As farmland mushroomed into split-level ranch houses and kitchens sprouted automatic toasters, the town, population 5,500, revolved around a brick-lined main street with just one soda fountain. It was, John Johnson told PBS' American Experience, “more or less a lazy type, laid-back” kind of place.

Wytheville only had two ambulances that summer when children started to get sick. At first, there were just a handful of cases, mostly young boys. Then doctors named the disease: polio. Eugene Warren, now an old man, can still remember the terror spreading. “It became more and more evident that we were really in trouble,” Warren said. “You just couldn’t pick up everybody and leave and you couldn’t set the whole town on fire. It was almost, not hopeless, but it was getting pretty close that way.” By the time the days began to get shorter again, 184 people in Wytheville had been paralyzed and 17 had died.

It would be difficult to overstate the fear that accompanied this disease. "I think," Eleanor Roosevelt said of her husband, “probably the thing that took the most courage in his life was his mastery and his meeting of polio.” But the same year that life in Wytheville shuddered to a halt, Dr. Hilary Koprowski developed the first oral polio vaccine. Today, in one of the great public health stories of the 21st century, thanks to a comprehensive vaccination program, polio has been completely eradicated in the United States.

One of the complications with coalition-led, large-scale public health programs is that calling into question basic strategies becomes very political.

Dr. Koprowski passed away this past weekend at the age of 96, but he was in no way guaranteed to die at home in his own bed. A Polish immigrant who fled from Europe in 1940, Koprowski was known to take risks with his research. His biographer described the first human test of Koprowski’s vaccine succinctly: Koprowski tried it himself. In January of 1948, he combined a greasy mixture of cotton rat spinal cord and brain tissue in an electric blender in Pearl River, New York. He had injected rounds of rats with batches of the polio virus, diluted by saline solution. As the rats developed the disease, their brains provided the basis for the next dilution, until Koprowski deemed the solution weak enough to test on monkeys. When the monkeys began producing antibodies rather than contracting polio, he took the latest solution, poured into a glass beaker, and knocked it back. According to his biographer, his assistant remembers Koprowski noting that it tasted like cod liver oil. “Have another?” the assistant joked. “Better not,” Koprowski said. “I’m driving.”

Thanks in part to Koprowski’s work, scientists now know that poliomyelitis, a contagious virus, is spread through fecal-oral transmission. Once inside the body, it multiplies in the small intestine before entering the central nervous system. In 99 out of 100 cases, it causes a mild fever and nausea, but in one percent of those infected, it develops into acute flaccid paralysis, destroying the nerve cells that contract muscles. The onset of the paralysis is rapid, and if it doesn’t stop before it reaches the lungs, the patient’s prognosis is grim—mortalities associated with polio most often come from suffocation.

Although polio is now eradicated in the U.S., and most of the rest of the world, there are still four countries struggling with the disease: Afghanistan, Nigeria, Pakistan, and India. But over the last 10 years, over $8 billion have been spent in the largest public health campaign ever designed, targeting polio in India, with the ambitious goal of proving the disease can be wiped from the globe.

The oral vaccine currently in use in India has changed since Koprowsi’s time, but the gist of the program is to regularly send basic oral vaccinations similar to the one he developed with community health workers door-to-door, reaching millions of houses, including migrant work sites and slums, as well as every train and bus station in high-risk areas.

The program has succeeded beyond epidemiologists’ wildest dreams: more than 2.3 million vaccine administrators have given vaccinations to 170 million children. The program has been lauded for innovative strategies of shepherding community buy-in, and for the difficulty of providing comprehensive coverage in places that lack even basic infrastructure. And more importantly, it has worked. For the last year, India hasn’t had any new cases of “wild” polio.

But “wild” just means naturally-occurring strains of the disease. That doesn’t mean that no cases of polio-related paralysis have been found. A paper published in the Indian Journal of Medical Ethics last year found 47,500 cases of “non-polio acute flaccid paralysis” (NPAFP), a polio-like paralysis that’s twice as deadly, and linked to the oral polio vaccine. According to data from the Centers for Disease Control, surveillance reports show that 16 people in India actually developed the disease between 2009 and 2011 from a “vaccine-derived virus”—which means the strain from the vaccine regained an ability to cause the disease itself.

Scientists have long known that the oral vaccine isn’t risk free—it’s created, obviously, from a living virus. Most countries, especially those in the developed world, have therefore switched to an injectable vaccine derived from dead strains. Although much of the global press surrounding India’s polio program has been—rightly—admiring, public health officials are now advocating that the campaign change its tactics. Last year, Stephen Cochi and Robert Linkins from the CDC went as far as publishing a study in the Journal of Infectious Diseases,calling for the “cessation of all OPV [oral polio vaccination].”

There are reasons why India’s campaign continues to rely on the oral vaccination: injectable vaccines are expensive, vaccinators would have to be more highly trained, and large investments would have be made to implement the kind of large-scale production capable of providing enough vaccines for India’s enormous program. Even entering into a conversation about using injectable vaccines is fraught with tension; one of the complications with coalition-led, large-scale public health programs is that calling into question basic strategies becomes very political, and making changes to program design can be dauntingly difficult.

Still, the goal of public health campaigns is, after all, health. The World Health Organization has called for a shift to injectable vaccines, and as India looks toward its certification—if there are no new cases of wild polio, the country will be declared polio-free in 2014—a critical eye will need to be turned to the next phase of keeping the disease at bay.

That’s something even Koprowski, a man who questioned the status quo all his life, would understand.