Universal use of inactivated polio vaccine

Abstract

Changes in the international scenario have demonstrated that the risks of vaccine-associated paralytic polio (VAPP) or paralysis caused by vaccine-derived poliovirus (VDPV) are higher than the risk of paralysis caused by wild viruses requiring that the oral polio vaccine (OPV) be replaced with the inactivated polio vaccine (IPV) as proposed by Falleiros-Carvalho & Weckx. The major issues related to the introduction of IPV in routine vaccine schedules are concerned with lower gastrointestinal immunity difficult application (parenteral use) availability and costs. Recent studies have revealed that children previously vaccinated with two doses of IPV had low fecal shedding of vaccine viruses after being challenged with one dose of OPV; moreover the risk of reversion of Sabin strains to neurovirulent forms did not increase after the use of IPV. Combined vaccines containing IPV improved the acceptance of the inactivated vaccine since they provide vaccine coverage against several diseases at lowercosts. In the last few years the number of countries using IPV in sequential schemes (IPV followed by OPV) or in exclusive ones has increased; however it has been estimated that only 100 million doses can be produced every year. The technology for IPV production has been well known for over five decades but only few laboratories are allowed to produce this vaccine and production of the vaccine is limited. (excerpt)