Pediatric Supersite
05/13/2010
Vaccine-derived poliovirus type 2 was detected in five of six documented cases of immunodeficiency-associated vaccine-derived polioviruses in Iran from 1995 to 2008 — indicating a global need to change to an inactivated polio vaccine schedule.
Researchers from several institutions in Iran reviewed these cases to define the prevalence of vaccine-associated paralytic poliomyelitis. They also aimed to determine whether changing to an inactivated polio vaccine schedule and screening neonates for immunodeficiencies could reduce the risk for infection.
The first patient was a 17-month-old girl who acquired the infection in 1995. She was administered the inactivated polio vaccine due to a known antibody deficiency. She also had a healthy sibling who was administered the oral polio vaccine. Fecal samples indicated vaccine-derived poliovirus type 2. Recombination with the Sabin 1 strain was detected, with a crossover site at nt 5355, according to the results.
The second case occurred in a 7-month-old boy in 2005. He had been administered the oral polio vaccine at birth and at 2, 4 and 6 months. His fecal samples also indicated vaccine-derived poliovirus type 2 and recombination with the Sabin 1 strain with a crossover site at nt 5358. He did not have HIV, but the expression of human leukocyte antigen DR on his lymphocytes was low, indicating major histocompatibility complex class II deficiency.