Vaccines and Immunoprophylaxis · USMLE Step 1

A child receives an oral polio vaccine in a country where it is still used. What advantage does OPV have over IPV?

  1. Higher overall safety profile
  2. Induces intestinal mucosal immunity
  3. Cannot revert to neurovirulence
  4. Requires only a single dose
Show answer and explanation

Correct answer: Induces intestinal mucosal immunity

OPV induces strong mucosal IgA immunity, reducing viral shedding and transmission. However, it has rare risks of reversion to virulence.

Difficulty: Medium Question 17 of 20

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