What is a vaccine-derived poliovirus?
A vaccine-derived poliovirus (VDPV) is a strain of polio virus, initially contained in the live OPV, that has changed over time and behaves more like a wild or naturally-occurring virus. This means it can be more easily spread to others who are unvaccinated against polio and who come in contact with the stool or oral secretions (e.g. saliva) of an infected person. These viruses may cause illness, including paralytic poliomyelitis.
