Which statement about immunization with IPV vs OPV is correct?

• A. IPV induces mucosal immunity and can cause VAPP.
• B. IPV induces systemic humoral immunity with limited mucosal immunity and no risk of VAPP; there is no fecal shedding.
• C. IPV induces neither humoral nor mucosal immunity.
• D. IPV induces strong mucosal immunity, equal to OPV.

Answer: (B)

The main idea here is how IPV and OPV differ in the type of immunity they induce and their safety features. IPV is an inactivated injectable vaccine. It mainly stimulates systemic humoral immunity, producing circulating antibodies that protect the bloodstream and nervous system, but it gives only limited mucosal immunity in the gut. Because it does not replicate in the gut, there is no fecal shedding after vaccination and no risk of vaccine-associated paralytic poliomyelitis (VAPP).

OPV, on the other hand, is a live attenuated oral vaccine. It replicates in the intestinal tract and elicits strong mucosal immunity in the gut, which helps block intestinal infection and transmission. However, its live nature carries a small risk of VAPP and possible shedding that can spread in under-immunized populations.

So the statement that IPV induces systemic humoral immunity with limited mucosal immunity and no risk of VAPP; there is no fecal shedding, best captures these distinctions.