Vaccine-Associated Paralytic Poliomyelitis
Vaccine-associated paralytic poliomyelitis is a rare adverse reaction to the live oral polio vaccine. The paralysis from this condition is identical to that caused by wild poliovirus, and may be permanent. Inactivated polio vaccine does not contain live poliovirus, so it cannot cause vaccine-associated paralytic poliomyelitis.
Vaccine-associated paralytic poliomyelitis is a rare adverse reaction that can occur following vaccination with the live oral polio vaccine (OPV). Inactivated poliovirus vaccine (the poliovirus vaccine currently used in the United States) does not contain live poliovirus, so it cannot cause vaccine-associated paralytic polio.
The mechanism of vaccine-associated paralytic poliomyelitis is believed to be a mutation, or reversion, of the vaccine virus. These mutated viruses are called revertants. Reversion is believed to occur in almost all vaccine recipients, but it only rarely results in paralytic disease. The paralysis is identical to that caused by wild poliovirus, and may be permanent.
Vaccine-associated paralytic poliomyelitis is more likely to occur in people who are 18 years of age and older than in children, and is much more likely to occur in immunodeficient children than in those who are immunologically normal. Compared with immunocompetent children, the risk of vaccine-associated paralytic poliomyelitis is almost 7,000 times higher for people with certain types of immunodeficiencies, particularly B-lymphocyte disorders, which reduce the synthesis of immune globulins. There is no procedure available for identifying people at risk of paralytic disease, except excluding older people and screening for immunodeficiency.