vaccine-derived poliovirus

Vaccine-derived poliovirus (VDPV) is a rare strain that originates from the weakened virus used in the oral polio vaccine (OPV). While OPV has been instrumental in nearly eradicating polio worldwide, in very rare instances, the live attenuated virus within the vaccine can mutate and regain virulence. These mutated strains, known as VDPVs, can cause paralysis and spread within populations that have low polio-immunization rates.123

There are different types of VDPVs, including circulating VDPVs (cVDPVs). The oral polio vaccine (OPV) itself can also cause vaccine-associated paralytic polio (VAPP) in a small number of recipients or their contacts. Due to these risks, many countries have transitioned to using the inactivated poliovirus vaccine (IPV), which does not carry the risk of VDPV or VAPP. However, OPV may still be used strategically in certain areas to enhance herd immunity.23