Regarding vaccine-associated paralytic polio (VAPP), which of the following is correct?
- A VAPP occurs at a rate of approximately 1 per 1 million doses of IPV
- B Type 2 OPV is the most common cause of VAPP and was withdrawn from use in 2016 ✓
- C VAPP only occurs in immunocompromised recipients, never in contacts
- D IPV has replaced OPV entirely in India's UIP since 2018
Correct answer: B. Type 2 OPV is the most common cause of VAPP and was withdrawn from use in 2016
Explanation
Serotype 2 of OPV (Sabin type 2) was responsible for the majority of circulating vaccine-derived poliovirus (cVDPV2) cases globally and was withdrawn with the global switch from tOPV (trivalent) to bOPV (bivalent types 1 and 3) in April 2016. VAPP occurs at a rate of approximately 1 per 2.7 million first doses of OPV (not IPV, which causes no VAPP as it is inactivated). VAPP can occur in both immunocompetent recipients (on rare occasions) and immunocompromised individuals, as well as contacts. India uses bOPV + IPV in a sequential schedule, not IPV alone.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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