Israel is in the midst of a massive, emergency immunization drive of all children under the age of 9 against polio.
Health workers detected the virus in southern Israel in February. Since then, they've found it in 85 different sewage samples across the country, the said Wednesday. Yet so far, no children have gotten sick or been paralyzed by the virus.
Israel has one of the highest rates of immunization coverage in the world, says Chris Maher of the World Health Organization. And that's one reason why the country has avoided polio cases, so far. But health officials are still very concerned about the situation.
The vaccination campaign aims to give polio boosters to a million children.
"There's no way that 100 percent of the population can be immune at any given time," Maher says. "So any time that virus is circulating [in the environment], if there's a person who's not immune, there's a risk that that person is going to get clinical polio. They're going to get infected, and they're going to get sick."
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