Efficacy and safety of oral poliovirus vaccine and inactivated poliovirus vaccine.

Inactivated poliovirus vaccine (IPV) is the vaccine of choice for protection against paralytic poliomyelitis provided that it is used within the context of a program to increase and sustain the level of uptake to as close to 100% as possible. This means targeting the disadvantaged in society as well as those who have their own pediatrician. The reasons are that enhanced-potency killed polio vaccine is safe, whereas oral poliovirus vaccine (OPV) is associated with a low, but definite, risk of paralysis, especially after the first dose. The immunity, as measured by antibody concentrations, is at least as good as and, in some circumstances, such as in the tropics or for booster doses, better than that provided by OPV. IPV reduces the replication of living poliovirus and produces herd immunity, as exemplified by experience in Sweden and Holland. The immunity, whether induced by OPV or IPV, involves memory cells and is long lasting, as seen by the rapid secondary response to a booster dose. IPV also can be mixed with other vaccine components to provide immunity against an increasing range of childhood infections.