In the 1950s,
Albert Sabin developed the
oral polio vaccine using a live but weakened form of the polio virus. While this form of vaccination allows recipients to develop full immunity and can even be transmitted to non-vaccinated individuals, conferring some immunity to them, mutated forms of the vaccine can actually spread the paralytic disease among those who have not been immunized. Recently, the UN's World Health Organization confirmed that a
Nigerian outbreak of
polio has been traced to such a mutation. Sixty nine children, about 5% of Nigeria's recent polio victims, have been diagnosed with the vaccine-induced viral disease.
