What Is a ‘Vaccine-Derived’ Poliovirus? - Voice of America - VOA News

Vaccine-derived viruses, which emerge when the weakened viruses in the oral polio vaccine mutate and spread in unvaccinated populations, still occasionally cause outbreaks

New York health officials announced in July that an unvaccinated adult man from Rockland County had been diagnosed with poliothe first case of the life-threatening disease in the United States since … [+6285 chars]

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