Explainer: Why has polio been found in London, New York and Jerusalem, and how dangerous is it?

Explainer: Why has polio been found in London, New York and Jerusalem, and how dangerous is it? Polio, a deadly disease that used to paralyze tens of thousands of children every year, is spreading in London, New York and Jerusalem for the first time in decades, spurring catch-up vaccination campaigns. Jennifer Rigby Reuters

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But experts agree that the major driver behind both vaccine-derived and wild polio outbreaks remains under-vaccinated populations, said Derek Ehrhardt, global polio lead at the United States Centers for Disease Control and Prevention (CDC)...