Question

Assertion (A): A child who has had an acute attack of poliomyelitis should be administered oral polio vaccine.

Reason (R): There is no cross-immunity between the different types of polio viruses.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Recall that OPV covers three separate poliovirus serotypes.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept.
Poliomyelitis is caused by one of three poliovirus serotypes (type 1, 2 or 3). An attack of paralytic polio due to one serotype leaves the child immune only to that one serotype, not to the other two.

Step 2: Key Formula or Approach.
Because oral polio vaccine (OPV) protects against all three serotypes, a child who has already suffered paralytic polio from one serotype still needs full OPV coverage to guard against the remaining two serotypes. So the assertion, that OPV should still be given, is true.

Step 3: Detailed Explanation.
The reason statement, that there is no cross-immunity between the poliovirus types, is also a true fact on its own. But the accepted rationale for continuing vaccination after an attack is broader than just this immunological fact. It is standard practice under the national immunization schedule to complete the full course of OPV in every child regardless of a past infection, both to build immunity against the untouched serotypes and because a single wild infection does not certify complete protection. The reason given only touches one part of this and is not treated as the full, direct explanation of the assertion in national guidelines.

Step 4: Final Answer.
So both A and R are individually true statements, but R is not the correct explanation of A.