Which vaccine is administered orally and induces intestinal immunity?

• A. Oral polio vaccine (OPV, Sabin vaccine)
• B. Inactivated polio vaccine (IPV)
• C. Measles vaccine
• D. Rotavirus vaccine

Answer: (A)

Oral administration with a focus on mucosal immunity in the gut. The oral polio vaccine uses a live attenuated poliovirus that replicates briefly in the intestinal lining. This replication stimulates local immune responses, especially secretory IgA in the gut, building intestinal immunity that helps prevent infection and reduces shedding of the virus. In contrast, the injected inactivated polio vaccine mainly triggers system-wide antibodies (like IgG) and provides strong protection from disease but does not generate as robust mucosal immunity in the gut. Rotavirus vaccine is also given by mouth and induces intestinal immunity, but it targets a different pathogen. So, the vaccine that is administered orally and induces intestinal immunity against poliovirus is the oral polio vaccine.