In the Global Polio Eradication Initiative (GPEI), the switch from trivalent OPV (tOPV) to bivalent OPV (bOPV) occurred in April 2016 because:
- A Serotype 1 poliovirus was eradicated, making its inclusion unnecessary
- B Serotype 3 poliovirus was the most common circulating type
- C Serotype 2 wild poliovirus was declared eradicated, and type 2 OPV was causing vaccine-derived poliovirus (cVDPV2) outbreaks ✓
- D IPV alone was sufficient to prevent all transmission globally
Correct answer: C. Serotype 2 wild poliovirus was declared eradicated, and type 2 OPV was causing vaccine-derived poliovirus (cVDPV2) outbreaks
Explanation
Wild poliovirus type 2 was declared eradicated in 2015, having last been detected in 1999. The type 2 component in tOPV was generating circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreaks. The global switch to bOPV (types 1 and 3 only) in April 2016, synchronized with one dose of IPV to maintain type 2 immunity, was implemented to eliminate this paradox.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.