Polio Vaccine Effectiveness and Duration of Protection

Vaccine Effectiveness

Two doses of inactivated polio vaccine (IPV) are 90% effective or more against polio; three doses are 99% to 100% effective.

A person is considered to be fully vaccinated if he or she has received:

  • four doses of any combination of IPV and tOPV, or
  • a primary series of at least three doses of IPV or trivalent oral poliovirus vaccine (tOPV)


  • The last dose in either series should be given after 4 years of age and at least 6 months after the previous dose.

Duration of Protection

It is not known how long people who received IPV will be immune to poliovirus, but they are most likely protected for many years after a complete series of IPV.

Page last reviewed: May 4, 2018