RARE VACCINE-DERIVED POLIO DISCOVERED IN 2 COUNTRIES

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RARE VACCINE-DERIVED POLIO DISCOVERED IN 2 COUNTRIES

By DONALD G. McNEIL Jr. New York Times, Nov. 14, 2014

Cases of paralysis caused by mutating polio vaccine have been found in South Sudan and Madagascar, the World Health Organization said Friday. New rounds of vaccination will be conducted in December in both areas. The two paralysis cases in South Sudan were in a displaced-persons camp where revaccination is relatively easy, the W.H.O. said, while testing suggests that the one case in Madagascar did not spread far. “Vaccine-derived polio paralysis” is a rare but small risk inherent in oral vaccine, so the polio eradication campaign is trying to introduce injectable vaccine wherever it is safe and practical. The injectable vaccine contains a “killed” virus that cannot mutate. But it provides less protection than the live, weakened virus in oral vaccine, is more expensive and is much harder to give. Only 279 cases of polio have been detected in the world this year, almost all of them in Pakistan or in Pakistani families in Afghanistan.