A 12-month-old child has previously received 3 doses of IPV under the UIP schedule. During a campaign, OPV is also administered. Which of the following best explains the rationale for 'supplementary' OPV campaigns alongside routine IPV in India?

• A IPV provides superior intestinal mucosal immunity compared to OPV
• B OPV is thermostable and easier to administer in field conditions
• C OPV induces better intestinal mucosal (secretory IgA) immunity, blocking poliovirus replication in the gut and fecal-oral transmission ✓
• D IPV-vaccinated children cannot shed poliovirus and do not need OPV

Explanation

IPV induces excellent systemic (humoral) immunity and prevents paralytic polio but provides limited intestinal mucosal immunity. OPV, being a live attenuated oral vaccine, replicates in the gut and generates strong secretory IgA at the intestinal mucosa, blocking wild poliovirus replication and fecal-oral transmission (herd immunity). In India, where environmental poliovirus circulation and fecal-oral transmission persist, supplementary OPV campaigns alongside routine IPV are needed to achieve intestinal mucosal immunity and interrupt transmission. Vaccine-derived poliovirus (VDPV) remains a risk of OPV, hence the combined strategy.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.