bOPV + IPV

bOPV + IPV is a combination vaccination approach used for polio prevention. It consists of bivalent oral poliovirus vaccine (bOPV) administered together with inactivated poliovirus vaccine (IPV). ## Composition and Administration bOPV + IPV is a sequential immunization schedule that combines: 1. **bOPV (bivalent Oral Polio Vaccine)**: Contains live attenuated poliovirus types 1 and 3 2. **IPV (Inactivated Polio Vaccine)**: Contains inactivated poliovirus types 1, 2, and 3 The typical dosage for children following the bOPV + IPV schedule is a 0.5 ml single dose of IPV at 14 weeks, administered in combination with a dose of bOPV[4]. This combination approach was implemented globally after the withdrawal of trivalent OPV (tOPV) in 2016[5]. ## Mechanism and Immunogenicity The combination of bOPV and IPV aims to provide immunity against all three poliovirus types. IPV provides immunity against types 1, 2, and 3, while bOPV specifically targets types 1 and 3[3][5]. This approach was developed because: - bOPV alone does not provide protection against poliovirus type 2 - IPV provides excellent humoral immunity but less intestinal immunity - The combination aims to provide comprehensive protection Studies have shown that children who receive IPV with bOPV demonstrate excellent seroconversion rates, particularly when administered at 6 months of age when interference with maternal antibodies is minimal[2]. However, research has not observed cross-mucosal immunity for poliovirus type 2 when a combination of IPV and bOPV is administered[2]. ## Global Implementation This sequential immunization strategy was implemented globally after April 2016, when all countries still using OPV stopped using trivalent OPV (tOPV) and switched to using bivalent OPV (bOPV) in routine immunization[3]. This switch was part of the global polio eradication initiative. For children who may have received only bOPV outside the United States, they are not considered vaccinated against type 2 poliovirus and need to complete an IPV 3- or 4-dose series depending on their age to be fully protected[3]. ## Considerations and Limitations Research has shown that immunization schedules involving one or two doses of IPV followed by bOPV failed to maintain a high positive rate for poliovirus type 2-specific antibodies over time[5]. This has implications for long-term protection against type 2 poliovirus. When nOPV2 (novel oral poliovirus vaccine type 2) is administered with bOPV, studies have shown reduced immunogenicity to poliovirus type 2 compared with trivalent OPV, which may necessitate three doses for full protection in vaccine-naive individuals[6].

Other names

bOPV + IPV sequential immunization schedule