Immunisation: conjugate vaccines: practice question

A Pediatrics question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

Try it

Pediatrics · Immunisation: conjugate vaccines

Sample item

Why is the Haemophilus influenzae type b capsular polysaccharide conjugated to a protein carrier in the vaccine given to infants?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. To make the response T-dependent

Plain polysaccharides are T-independent antigens that are poorly immunogenic below 2 years and give no memory. Linking them to a protein recruits T-helper cells, giving a good infant response, memory and a booster effect. Hib is included in the pentavalent vaccine for this reason.

Option by option

  • A. To make the vaccine a live attenuated organism

    The conjugate vaccine is an inactivated antigen, not a live organism.

  • B. To stimulate only mucosal IgA

    Conjugate vaccines induce systemic IgG, not only mucosal IgA.

  • C. To make the response T-dependent (correct)

    Correct. Conjugation brings T-cell help, so infants respond and develop memory.

  • D. To allow a single dose to give lifelong immunity

    Several doses are still needed; conjugation does not give one-dose lifelong immunity.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Pediatrics questions

Questions about this Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, To make the response T-dependent. Plain polysaccharides are T-independent antigens that are poorly immunogenic below 2 years and give no memory.

Why is "To make the vaccine a live attenuated organism" not the answer?

The conjugate vaccine is an inactivated antigen, not a live organism.

Why is "To stimulate only mucosal IgA" not the answer?

Conjugate vaccines induce systemic IgG, not only mucosal IgA.

Why is "To allow a single dose to give lifelong immunity" not the answer?

Several doses are still needed; conjugation does not give one-dose lifelong immunity.

What concept does this question test?

It tests Immunisation: conjugate vaccines in Pediatrics. Linking them to a protein recruits T-helper cells, giving a good infant response, memory and a booster effect. Hib is included in the pentavalent vaccine for this reason.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Immunisation: conjugate vaccines?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.