On January 13, India became the latest country to celebrate a year completely polio-free. After more than a century as a global scourge and hundreds of thousands lives lost, polio may now be on the verge of being the second human disease wiped off the face of the Earth -- after smallpox, which was eradicated 36 years ago. But the global battle to defeat polio is expensive -- and we're by no means sure of victory. That does raise the question: is it worth it?
In 1952, more than 50,000 kids were paralyzed by a polio outbreak in the United States. Today, the disease is unknown in America -- and across much of the rest of the world. In 1981, there were more than 65,000 new cases reported worldwide to the World Health Organization. That number dropped to 1,348 in 2010 and 628 in 2011. That progress has saved as many as five million kids from paralysis worldwide and is thanks to a global effort involving millions of volunteers, health workers, and government officials, as well as the World Health Organization, UNICEF, and the Rotary and Gates Foundations.
Despite this heartening success, getting all the way to eradication is proving immensely hard. In 2010, the majority of polio cases were in countries once free of the virus. In 2011, six countries that had been polio-free the previous year saw the disease come back -- although the good news is that incidents were few: only 66 cases between them. Unlike smallpox, most cases of polio don't show any immediate symptoms, which complicates the response to outbreaks. Moreover, vaccinating against the disease takes repeated doses (India's polio-free year involved two nationwide programs in 2011, each immunizing 172 million children over five days).
And, of course, global eradication depends crucially on parents being willing to vaccinate their kids in the countries still suffering outbreaks -- not least Pakistan and Nigeria. Both countries have faced opposition to vaccination programs on the grounds that they are a Western plot to sterilize local girls. Sadly, these wild conspiracy theories were given an additional patina of credibility last year by the revelation that the CIA used a vaccination program to cover its attempts to get DNA samples from Osama bin Laden's children in Abbottabad. Perhaps polio eradication will be another victim of the war on terror.
In part because of the considerably greater complexity of the vaccination program, the cost of the polio eradication program is mounting. Over the disease's last decade in the 1970s, the cost of the global smallpox eradication effort was roughly $330 million. Getting India to zero polio cases last year involved a program that has already cost $2 billion, and the worldwide price tag tops $1 billion each year.
Adding to the uncertainty and the cost, there's a small risk using the standard oral vaccination --which contains a weakened live version of the virus -- that the polio virus actually re-emerges at full strength after a time sitting in the guts of vaccinated kids. So, if we want to be fully sure of wiping out the disease using today's approaches, even many "polio-free" countries would have to continue vaccinating children for five or ten more years using an injectable inactivated polio vaccine -- which is more expensive and complex to administer than the oral vaccine.
Every year, then, we're putting down $1 billion more on a gamble that we can eradicate the disease -- a gamble we're by no means sure of winning. Meanwhile, the very success of the vaccination campaign to date means that polio just isn't a major public health threat any more. Consider that the global count of polio cases last year, at 628, equals the number of people who died of malaria in Papua New Guinea in 2008. Worldwide, the mosquito-borne disease kills nearly two thirds of a million people a year, yet the international program to roll back malaria sees funding of only about $1.6 billion a year. That's led some to suggest it's time to cut our losses with polio (or declare partial victory) and go on to other scourges. Richard Horton, who edits the British medical journal The Lancet, has suggested that the polio eradication drive is diverting dollars from other health priorities.