Poliovirus type 2 was declared eradicated globally in 2015, yet type 2-containing Oral Polio Vaccine (tOPV) was withdrawn in 2016. The PRIMARY reason for tOPV withdrawal and switch to bOPV was:
- A Type 2 IPV was more immunogenic than type 2 OPV
- B Circulating vaccine-derived poliovirus type 2 (cVDPV2) was the main remaining paralytic polio risk ✓
- C tOPV production was costlier than bOPV
- D Type 1 and 3 strains were more virulent and needed concentrated coverage
Correct answer: B. Circulating vaccine-derived poliovirus type 2 (cVDPV2) was the main remaining paralytic polio risk
Explanation
After wild poliovirus type 2 eradication, continuation of tOPV paradoxically became the main source of polio risk through circulating vaccine-derived poliovirus type 2 (cVDPV2), which can emerge when Sabin type 2 virus in OPV reverts to neurovirulence in under-immunized populations. The synchronized global switch from tOPV to bOPV (types 1+3) in April 2016 was accompanied by introduction of at least 1 dose of IPV (covering type 2) in all national immunization schedules to maintain type 2 immunity. This was a landmark coordinated global health action.
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.