Which vaccine provides robust intestinal immunity against poliovirus?

• A. IPV
• B. Both
• C. OPV
• D. Neither

Answer: (C)

Robust intestinal immunity against poliovirus comes from vaccines that replicate in the gut and trigger mucosal immune responses. The oral polio vaccine is a live attenuated vaccine given by mouth; it replicates in the intestinal tract and elicits strong mucosal immunity, including secretory IgA, in the gut. This mucosal response helps prevent infection and reduces viral shedding in the intestines, limiting transmission. Inactivated polio vaccine, while excellent at producing systemic neutralizing antibodies and protecting against paralytic disease, does not induce the same level of mucosal immunity in the gut. So, the oral polio vaccine provides the strongest intestinal immunity.