Poliovirus vaccination: a trilogy.

The incidence of poliomyelitis has declined dramatically since the introduction and widespread use of inactivated (IPV) and live oral (OPV) poliovirus vaccines. In the United States, fewer than 10 cases of paralytic poliomyelitis are reported each year, and all cases are vaccine associated. In contrast, paralytic disease due to wild virus continues to be a problem in less developed nations, in part due to poor seroconversion rates after receipt of OPV. The recent introduction of enhanced potency IPV has stimulated the prospects for a combined vaccine schedule that will reduce the frequency of vaccine-associated paralytic polio and retain good mucosal protection. Recent studies suggest that two doses of enhanced potency IPV followed by two doses of OPV provide excellent systemic and local immunity against polioviruses 1, 2, and 3.