India was certified polio-free by WHO in March 2014. The global strategy to achieve polio eradication now includes using novel oral polio vaccine type 2 (nOPV2) after a circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreak. Which best explains why monovalent OPV type 2 was removed from the routine NIS?
- A It caused more AEFI than bivalent OPV (bOPV)
- B After wild poliovirus type 2 eradication in 1999, continued use risked cVDPV2 emergence ✓
- C mOPV2 had lower seroconversion rates than IPV for type 2
- D bOPV provides equivalent type 2 immunity without any additional dose
Correct answer: B. After wild poliovirus type 2 eradication in 1999, continued use risked cVDPV2 emergence
Explanation
Wild poliovirus type 2 was declared eradicated in 1999. Continued use of OPV containing type 2 Sabin strain posed an ongoing risk of circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreaks through prolonged replication in under-immunized communities. Therefore in April 2016 (the 'Switch'), all countries using trivalent OPV globally switched to bivalent OPV (types 1 and 3) plus at least one dose of IPV for type 2 protection.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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