Vaccine-derived Poliovirus

Questions and Answers

What is a vaccine-derived poliovirus?

A vaccine-derived poliovirus (VDPV) is a strain of the weakened poliovirus that was initially included in oral polio vaccine (OPV) and that has changed over time and behaves more like the wild or naturally occurring virus. This means it can be spread more easily to people who are unvaccinated against polio and who come in contact with the stool or respiratory secretions, such as from a sneeze, of an infected person. These viruses may cause illness, including paralysis.

For this reason, the global eradication of polio requires stopping all OPV in routine immunization, as soon as possible after the eradication of wild poliovirus (WPV) transmission.  To protect against all three types of WPV, the United States exclusively has used IPV since 2000. For more information on OPV cessation, please visit the Global Polio Eradication Initiative’s websiteexternal icon.

What is vaccine-associated paralytic polio?

Vaccine-associated paralytic poliomyelitis (VAPP) is an adverse event following exposure to OPV. OPV is made with live attenuated (weakened) polioviruses that can result in a case of VAPP. VAPP is sporadic and rare. There is very little evidence that the vaccine virus circulates from VAPP cases, and there are no outbreaks associated with VAPP.

Is there a difference in a disease caused by a VDPV and one cause by wild poliovirus or OPV?

No, there is no clinical difference between the paralysis caused by wild poliovirus, OPV, or VDPV.

Has VDPV been found in the United States?

In 2005, a VDPV was found in the stool of a child in Minnesota who was not vaccinated and had a weakened immune system. The child most likely caught the virus through contact in the community with someone who had received live oral vaccine (OPV) in another country two months before. Subsequently, seven other unvaccinated children in the Minnesota community were found to have poliovirus infection. None of the infected children had paralysis. For more information about this case, visit pdf icon[7 pages]external icon.

Also in 2005, a healthy, unimmunized young adult from the United States acquired vaccine-associated paralytic polio (VAPP) in Central America, most likely from an infant grandchild of the host family who recently had been immunized with OPV. For more information about this case, visit

In 2009, an adult with a weakened immune system developed VAPP and died of polio-associated complications. VDPV was isolated, and the infection likely occurred where her child received OPV 12 years before.

In 2013, a fatal case was reported in an infant who received OPV in India and was severely immunocompromised.

Where do vaccine-derived polioviruses come from, and should I be concerned if there is a case in the United States?

VDPVs can cause outbreaks in countries where vaccine coverage is low. Long-term excretion can also occur in people with certain immunodeficiency disorders. Because OPV has not been used in the United States since 2000 and vaccine coverage with IPV is high, it is unlikely that any vaccine-derived poliovirus (VDPV) would become widespread in the United States.

Also, polio vaccination protects people against naturally occurring polioviruses and vaccine-derived polioviruses.

Page last reviewed: May 4, 2018