Question 1

Vaccine-derived poliovirus outbreaks are caused by the Inactivated Polio Vaccine (IPV) mutating in children's bodies.

Accepted Answer

Vaccine-derived poliovirus ONLY arises from the Oral Polio Vaccine (OPV), which contains a live, weakened virus capable of replicating and mutating in the gut. IPV contains a dead/killed virus that cannot mutate or cause disease.

Question 2

nOPV2 is now being given to all children globally as part of routine daily immunization.

Accepted Answer

nOPV2 is strictly reserved as an outbreak-response tool, deployed only in targeted regions actively experiencing circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreaks.

Question 3

Consider the following statements regarding the Novel Oral Polio Vaccine type 2 (nOPV2) and its WHO Prequalification:
1. nOPV2 holds the distinction of being the first vaccine in history to receive a WHO Emergency Use Listing (EUL).
2. India's Biological E. Limited is the first company in the world to receive end-to-end Phase II manufacturing WHO prequalification for nOPV2.
3. nOPV2 eliminates the risk of vaccine-derived poliovirus by utilizing an inactivated, killed virus that cannot replicate in the human gut.

How many of the statements given above are correct?

Accepted Answer

(a) Only one — Statement 1 is correct; nOPV2 was the first vaccine to receive WHO EUL in late 2020. Statement 2 is incorrect; Indonesia's PT Bio Farma was the first manufacturer to receive full prequalification, making Biological E the second. Statement 3 is incorrect; nOPV2 is a live-attenuated vaccine (not inactivated) that replicates in the gut to provide mucosal immunity, but it is genetically modified to be stable and resist mutation.

Question 4

Match List I (Vaccine Type) with List II (Characteristic/Use) regarding the global polio eradication strategy:

List I:
A. mOPV2 (Monovalent OPV2)
B. nOPV2 (Novel OPV2)
C. IPV (Inactivated Polio Vaccine)
D. bOPV (Bivalent OPV)

List II:
1. Replaced the trivalent vaccine in routine global immunization schedules in 2016.
2. First vaccine to ever receive the WHO Emergency Use Listing (EUL).
3. Traditional outbreak response tool that was frequently prone to seeding new cVDPV2 outbreaks.
4. Administered via injection; provides excellent systemic immunity but poor gut mucosal immunity.

Select the correct answer using the code given below:

Accepted Answer

(a) A-3, B-2, C-4, D-1 — mOPV2 (A) was the traditional Sabin outbreak response vaccine that notoriously seeded new variant outbreaks (3). nOPV2 (B) is the genetically stabilized vaccine that received the first EUL (2). IPV (C) is a killed, injectable vaccine providing systemic, but limited mucosal immunity (4). bOPV (D) replaced trivalent OPV in 2016 to stop routine use of the type 2 Sabin strain (1).

Question 5

Assertion (A): The traditional Sabin monovalent oral polio vaccine type 2 (mOPV2) is currently the preferred tool by the WHO for routine response to circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreaks.
Reason (R): The live attenuated virus in traditional OPV can genetically mutate in under-immunized populations, regain neurovirulence, and cause paralysis.

Select the correct answer from the codes given below:

Accepted Answer

(d) A is false but R is true. — The Assertion is false. mOPV2 is no longer the preferred tool because of its instability; it has been replaced by nOPV2 for cVDPV2 outbreak responses. The Reason is true. It accurately describes the fundamental flaw of the traditional OPV—its ability to revert to neurovirulence in the gut of under-immunized populations, which is exactly why cVDPV outbreaks occur.

WHO Prequalification for nOPV2 Vaccine

SC Issues Fresh Directions Restricting Adjournment Circulation