Questions

Poliovirus — Questions

Study questions about Poliovirus — exam-style, clinical-scenario and FAQ.

Mock Exam mode

Sit this set one question at a time. Multiple-choice questions mark themselves; written questions reveal a tickable mark scheme so you can score your own answer. You get a combined score at the end.

5 questions: 4 MCQ, 1 written.

High-priority (past-paper) questions only

A complete answer first checks existing immunity, then separates live from inactivated vaccines and sequences the doses within the time available.

Assessment first. Take a vaccination history and, where useful, check serology (measles, rubella, varicella, hepatitis B). Do a pregnancy test: the live vaccines (MMR and varicella) are contraindicated in pregnancy, and pregnancy should be avoided for one month after them.

Live vaccines (give on the same day, or at least 4 weeks apart).

MMR: one or two doses depending on documented immunity.
Varicella: two doses 4 to 8 weeks apart if there is no history or evidence of immunity.

Inactivated vaccines (flexible timing, may be co-administered at separate sites).

Hepatitis A: two doses at 0 and 6 to 12 months.
Hepatitis B: three doses at 0, 1 and 6 months (an accelerated 0, 7, 21 days plus a 12-month dose if time is short). Combined hepatitis A and B is an option.
Typhoid: single-dose Vi polysaccharide (inactivated).
Polio: an inactivated polio (IPV) booster.
dTaP: a single adult Tdap dose, reviewing tetanus and diphtheria status.

A workable sequence. Day 0: MMR, varicella (1), hepatitis A (1), hepatitis B (1), IPV, Tdap and typhoid together at separate sites. Then varicella (2) at 4 to 8 weeks; hepatitis B (2) at 1 month and (3) at 6 months; hepatitis A (2) at 6 to 12 months. Document everything for the destination country’s entry requirements.

Circulating vaccine-derived poliovirus (cVDPV) arises when the live oral vaccine strain reverts toward virulence and spreads in under-immunised communities. It drives the move to newer oral vaccine strains and to inactivated vaccine.

The other terms describe naturally circulating virus or unrelated immunological phenomena.

Wild poliovirus type 1 is now endemic in only two countries, Afghanistan and Pakistan. Vaccine-derived strains circulate more widely, so the affected-country list changes and must be checked at the time of travel.

Nigeria and India are among the countries that have interrupted wild poliovirus transmission.

Being injected, the inactivated vaccine raises serum antibody but little mucosal immunoglobulin A, so it does not stop the virus replicating in and shedding from the gut. It protects the individual from paralysis without fully interrupting transmission, the reason oral vaccine is still used for outbreak control.

It does induce serum antibody, individual protection and memory, and it does prevent invasion of the nervous system.

Long-stay travellers leaving an affected country may be required to show a polio dose received between 4 weeks and 12 months before departure, documented on the certificate. The measure aims to stop travellers exporting the virus across borders.

Childhood doses alone, natural immunity or stool testing do not satisfy the requirement.

High priorityExam-styleA 26-year-old woman requires vaccination before emigrating and needs hepatitis A, hepatitis B, typhoid, measles-mumps-rubella (MMR), varicella, polio and diphtheria-tetanus-acellular pertussis (dTaP). Give your advice and a proposed vaccination schedule. [7]
Model answer
A complete answer first checks existing immunity, then separates live from inactivated vaccines and sequences the doses within the time available.

Assessment first. Take a vaccination history and, where useful, check serology (measles, rubella, varicella, hepatitis B). Do a pregnancy test: the live vaccines (MMR and varicella) are contraindicated in pregnancy, and pregnancy should be avoided for one month after them.

Live vaccines (give on the same day, or at least 4 weeks apart).
- MMR: one or two doses depending on documented immunity.
- Varicella: two doses 4 to 8 weeks apart if there is no history or evidence of immunity.
Inactivated vaccines (flexible timing, may be co-administered at separate sites).
- Hepatitis A: two doses at 0 and 6 to 12 months.
- Hepatitis B: three doses at 0, 1 and 6 months (an accelerated 0, 7, 21 days plus a 12-month dose if time is short). Combined hepatitis A and B is an option.
- Typhoid: single-dose Vi polysaccharide (inactivated).
- Polio: an inactivated polio (IPV) booster.
- dTaP: a single adult Tdap dose, reviewing tetanus and diphtheria status.
A workable sequence. Day 0: MMR, varicella (1), hepatitis A (1), hepatitis B (1), IPV, Tdap and typhoid together at separate sites. Then varicella (2) at 4 to 8 weeks; hepatitis B (2) at 1 month and (3) at 6 months; hepatitis A (2) at 6 to 12 months. Document everything for the destination country’s entry requirements.
MCQ
A polio outbreak caused by reversion of the live oral vaccine to a virulent, transmissible form is termed:
- A. Naturally occurring wild-type poliovirus
- B. Primary failure of the vaccine to take
- C. Vaccine-associated enhanced viral disease
- D. Original antigenic sin from prior exposure
- E. Circulating vaccine-derived poliovirus
Show answer
Correct answer: E
Circulating vaccine-derived poliovirus (cVDPV) arises when the live oral vaccine strain reverts toward virulence and spreads in under-immunised communities. It drives the move to newer oral vaccine strains and to inactivated vaccine.

The other terms describe naturally circulating virus or unrelated immunological phenomena.
MCQ
As of 2026, wild poliovirus type 1 remains endemic in:
- A. Nigeria and Chad
- B. Afghanistan and Pakistan
- C. India and Bangladesh
- D. Syria and Yemen
- E. The Democratic Republic of the Congo
Show answer
Correct answer: B
Wild poliovirus type 1 is now endemic in only two countries, Afghanistan and Pakistan. Vaccine-derived strains circulate more widely, so the affected-country list changes and must be checked at the time of travel.

Nigeria and India are among the countries that have interrupted wild poliovirus transmission.
MCQ
Inactivated poliovirus vaccine prevents paralytic polio but, unlike the oral vaccine, does not efficiently:
- A. Block replication of poliovirus in the gut
- B. Induce serum neutralising antibody
- C. Protect the vaccinated individual
- D. Prevent viral invasion of the central nervous system
- E. Generate immunological memory
Show answer
Correct answer: A
Being injected, the inactivated vaccine raises serum antibody but little mucosal immunoglobulin A, so it does not stop the virus replicating in and shedding from the gut. It protects the individual from paralysis without fully interrupting transmission, the reason oral vaccine is still used for outbreak control.

It does induce serum antibody, individual protection and memory, and it does prevent invasion of the nervous system.
MCQ
Under the polio public health emergency, a traveller residing more than four weeks in a country with poliovirus circulation may be required to show:
- A. A polio dose received 4 weeks to 12 months before departure
- B. A single polio dose received at any time in infancy
- C. Three documented doses of inactivated polio vaccine before travel
- D. Documentary proof of natural polio immunity
- E. A recent negative stool sample for poliovirus
Show answer
Correct answer: A
Long-stay travellers leaving an affected country may be required to show a polio dose received between 4 weeks and 12 months before departure, documented on the certificate. The measure aims to stop travellers exporting the virus across borders.

Childhood doses alone, natural immunity or stool testing do not satisfy the requirement.