Why the world is not yet done with polio

The crippling virus has been almost eliminated—but stubborn pockets remain. The finish line for eradicating polio worldwide can seem like a weary marathoner’s mirage. The distance traveled is immense: The disease is now endemic in only three countries around the globe—Afghanistan, Nigeria, and Pakistan—and its incidence has decreased by more than 99 percent from an estimated 350,000 cases in 1988. (Endemic is the term used to describe countries with an ongoing incidence of the disease.) But we’re not quite there yet, as this year’s spring outbreaks in previously polio-free Somalia and Kenya reminded us. In addition, the discovery of sewage samples containing poliovirus in Israel has led to a countrywide campaign to offer oral polio vaccines to children between the ages of four months and nine years, as a precaution. No cases have appeared in Israel. And the numbers of those affected in Somalia and Kenya are small—110 as of August 7—with 177 reported...