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Fractional-dose IPV noninferior to full-dose IPV
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Researchers in Cuba reported similar immune responses in recipients administered with fractional-dose inactivated poliovirus vaccine compared with the full-dose formulation, suggesting a fractional dose is more cost-effective and better for outbreak control.
“Despite the support of the Global Alliance for Vaccines and Immunization, the affordability of IPV remains an issue for developing countries,” Sonia Resik, MD, PhD, from the Pedro Kouri Institute of Tropical Medicine in Cuba, and colleagues wrote in The Journal of Infectious Diseases. “Several approaches could make [inactivated poliovirus vaccine (IPV)] more affordable and may result in dose sparing, including the use of fractional-dose IPV (fIPV).”
The investigators performed a controlled, noninferiority study to compare immune responses following fIPV given intradermally and full-dose IPV given intramuscularly among oral poliovirus-vaccinated adults in Cuba. Resik and colleagues sought to safely reach seroconversion or increase antibody titer by 4 times or more. The noninferiority limit was 10%. On days 0 and 28 of the study, researchers randomly administered fIPV or IPV and then used a neutralization assay to analyze collected serum on days 0, 7, 28 and 56.
Of the 534 participants, 503 (94.2%) completed all study requirements. Researchers found that 28 days after the first dose, 94.8% of fIPV recipients had an immune response to poliovirus type 1, and immune response to poliovirus type 2 and 3 were both 98%. Comparatively, the immune response rates to poliovirus 1, 2 and 3 in the IPV arm were 98.1% (P = .06), 98% (P = 1), and 99.2% (P = .45). One days 7, 28 and 56, fIPV achieved noninferiority across all three serotypes. There were no reported serious adverse events.
“fIPV could be used in all individuals previously vaccinated against polio, such as in campaigns to control outbreaks,” Resik and colleagues wrote. “This option is both cost and dose sparing, allowing limited IPV to be stretched to vaccinate additional individuals.” – by Savannah Demko
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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The World Health Assembly resolved in 1998 to eradicate poliomyelitis globally by 2000. Substantial progress has been made, but the live-attenuated oral vaccine can be associated with paralysis in rare vaccine recipients. For that reason, the public health community is working to entirely replace the oral polio vaccine (OPV) with IPV. However, IPV is much more expensive than OPV. A study was conducted in Cuba to see if adults who had been previously vaccinated with OPV could be boosted with two fractional doses (reduced amount) of IPV. The study showed that reduced doses of IPV were very successful in generating an extremely high immune response. Additional studies are needed to see if reduced doses can be used in individuals who have not been previously immunized and whether these results can be replicated in other populations. The results suggest that fractional IPV doses could be used to boost immunity during a polio outbreak.
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