Which statement about switching from trivalent OPV to bivalent OPV with IPV is correct?

• A. To remove all vaccines worldwide.
• B. To remove the type 2 component to reduce VDPV2 while preserving PV1 and PV3 immunity; IPV provides systemic immunity.
• C. It is to switch to IPV only and stop OPV entirely.
• D. It is to increase mucosal immunity to all serotypes.

Answer: (B)

Switching from trivalent OPV to a bivalent OPV with IPV focuses on safety while preserving protection where it matters. By removing the type 2 component from OPV, the risk of vaccine-derived poliovirus type 2 (VDPV2) circulating in communities is greatly reduced. At the same time, immunity against types 1 and 3 is still maintained through the OPV that remains in use (bivalent), so protection against paralytic disease from those serotypes is preserved. Adding IPV provides systemic immunity—antibodies in the blood that protect the individual if exposure occurs—even though IPV doesn’t create strong mucosal immunity in the gut to block transmission as effectively as OPV. So the goal is to cut VDPV2 risk while keeping protection against poliovirus types 1 and 3, with IPV covering type 2 systemically.