Immunogenicity of mOPV1 and IPV in the EPI Schedule of India

In 2016, the Global Polio Eradication Initiative (GPEI) recommended stopping the use of type 2 oral poliovirus vaccine (OPV) and shifting from trivalent to bivalent OPV (bOPV), alongside the inclusion of inactivated poliovirus vaccine (IPV) in routine immunization. The GPEI strategy for 2022-2026 includes plans to cease bOPV use and transition to IPV alone or combined vaccine schedules.

The goal of a recent study was to assess the immunogenicity of monovalent OPV type 1 (mOPV1) with IPV and IPV-only schedules.

This three-arm, multi-center randomized-controlled trial was conducted in India during 2016-2017. The study involved newborns assigned to one of three schedules – bOPV-IPV (Arm A), mOPV1-IPV (Arm B), or IPV-only (Arm C). Serum samples were collected at birth, 14, 18, and 22 weeks and analyzed for all three poliovirus serotypes using a standard microneutralization assay.

Data from 598 participants were analyzed. The type 1 cumulative seroconversion rates four weeks post-schedule completion (at 18 weeks) were – 99.5% (Arm A), 100.0% (Arm B), and 96.0% (Arm C). Type 2 and type 3 seroconversions at 18 weeks were – 80.0% and 93.2% in Arm A, 76.9% and 100.0% in Arm B, and 81.9% and 99.4% in Arm C, respectively.

The findings demonstratehigh efficacy for type 1 poliovirus across all vaccine schedules – with mOPV1 showing non-inferior seroconversion to bOPV. All vaccines provided strong type-specific immunogenicity. The results support the use of various vaccines or schedules based on epidemiological needs, enhancing confidence in the polio eradication strategy. Future strategies may include bOPV + IPV post-switch, mOPV1 + IPV for WPV1 eradication, and IPV alone post-WPV eradication certification, with novel oral poliovirus vaccines addressing vaccine-derived poliovirus(VDPV) outbreaks.

Source:Mohanty L, John TJ, Pawar SD, et al. Vaccines. 2024 Apr 17;12(4):424.