Vaccine-derived polioviruses

[Sadsack]

Well, I learned something new today. There is a form of polio that is contagious (person to person) that originated with polio vaccinations.

Vaccine-derived polioviruses


Vaccine-derived polioviruses

Vaccine-derived polioviruses (VDPV) are defined as live, attenuated strains of the virus contained in the oral polio vaccine (OPV) which have changed and reverted to a form that can cause paralysis in humans with the capacity for sustained circulation. VDPVs differ from the parental (original) Sabin strains found in the vaccine by 1 to 15% of VP1 nucleotides. This is a measurement of genetic change that scientists use to monitor the circulation of viruses.

1. cVDPVs (circulating vaccine-derived polioviruses) that are associated with sustained person-to-person transmission and considered to be circulating in the environment;
2. iVDPVs (immunodeficiency related vaccine-derived poliovirus) isolated from immunodeficient patients who have prolonged infections after exposure to OPV; and
3. aVDPVs (ambiguous vaccine-derived poliovirus) isolated from a single immunocompetent AFP or paralytic poliomyelitis patient with or without additional isolates from contacts, or from healthy individuals or the environment in absence of paralytic cases.

SS