Vaccine-Associated Paralytic Polio (VAPP)
Definition and Mechanism
- Vaccine-associated paralytic polio (VAPP) is a rare but serious adverse event characterized by paralysis that occurs as a result of the oral poliovirus vaccine (OPV), caused by reversion of the attenuated vaccine virus to a more neurovirulent form 1, 2
- The condition can result in permanent paralysis and, in rare cases, death 2
Epidemiology and Risk Factors
- VAPP can occur in both vaccine recipients and in contacts of vaccinees who are exposed to the vaccine-derived virus 1, 2
- Immunodeficient individuals are at substantially increased risk for VAPP 3
- Persons with congenital immunodeficiency disorders are at increased risk for VAPP 4, 5
- Adults have a slightly higher risk of VAPP than children 6
Clinical Presentation and Diagnosis
- In contacts of vaccinees, paralysis can occur within approximately 4-6 weeks after exposure 7
Prevention and Management
- The United States switched from OPV to inactivated poliovirus vaccine (IPV) in 2000 specifically to eliminate the risk of VAPP while maintaining high levels of protection against wild polioviruses 8, 9
- IPV does not cause VAPP because it contains killed virus that cannot revert to neurovirulence 8
- For individuals at higher risk of exposure to wild poliovirus, IPV is preferred over OPV due to the risk of VAPP 6
- OPV should not be administered to immunodeficient individuals or their household contacts; IPV is recommended instead 5, 3
- If OPV is inadvertently given to a household contact of an immunodeficient person, the OPV recipient should avoid close contact with the immunodeficient person for 4-6 weeks 7