What is Vaccine-Derived Polio?
Vaccine-derived polio occurs when the weakened poliovirus used in the oral polio vaccine (OPV) mutates and regains the ability to cause paralysis.
The OPV contains a live, weakened virus that can replicate in the intestines and be shed in feces.
Rarely, this virus can mutate and cause disease in areas with low vaccination rates or poor sanitation.
If this mutated virus spreads in the community and is detected in multiple sources over time, it is classified as circulating vaccine-derived poliovirus (cVDPV2)
Types of Poliovirus
Wild Poliovirus Type 1 (WPV1): Most common and can cause severe polio outbreaks.
Wild Poliovirus Type 2 (WPV2): Eradicated as of 2015.
Wild Poliovirus Type 3 (WPV3): Eradicated as of 2019.
All types of wild polioviruses cause similar symptoms but differ in their geographical spread and impact.
More About Polio Vaccines
Inactivated Polio Vaccine (IPV):
Developer: Jonas Salk, 1950s.
Contains inactivated (killed) virus particles.
Administration: Injected into the muscle.
Advantage: No risk of causing vaccine-associated polio; induces systemic immunity.
Oral Polio Vaccine (OPV):
Developer: Albert Sabin, 1960s.
Contains live, weakened virus.
Administration: Given orally
Advantage: Easier to administer and less expensive; provides community-wide immunity.
Rarely, the weakened virus can revert and cause polio.
Current Status
In 2020, a modified type 2 oral polio vaccine (nOPV2) was introduced to reduce the risk of type 2 vaccine-derived poliovirus.
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