When Can We Stop Using Oral Poliovirus Vaccine?

In the years before the introduction of live, attenuated oral poliovims vaccine (OPV), there was a vigorous debate between advocates of killed and live vaccines. Proponents of live vaccine took the position that OPV would produce immunity more similar to that produced by wild viruses, providing superior individual and population protection. Proponents of inactivated poliovims vaccine (IPV) felt that there was a risk that attenuated viruses would regain their virulence and that person-to-person spread could permit continuous circulation of vaccine virus. On the basis of 50 years of experience with Salk' s killed poliovirus vaccine and MO years of experience with Sabin' s live, attenuated OPV, who was right? As is so often the case, both sides were. The first killed vaccine significantly reduced, but did not eliminate, polio. Mass campaigns with 3 monovalent OPVs brought the number of polio cases close to 0 in the United States. Although monovalent OPVs proved impractical for routine use, high coverage with trivalent OPV eliminated the disease from the United States; the last case caused by wild virus occurred