A 2-month-old infant receives pentavalent vaccine (DTP-HBV-Hib). Which component of this vaccine has the highest risk of causing a serious adverse event (grade 3 or higher systemic reaction)?

• A Hepatitis B surface antigen (HBsAg) component
• B Hib polysaccharide-protein conjugate
• C Whole-cell pertussis component ✓
• D Tetanus toxoid component

Explanation

The whole-cell pertussis (wP) component of the pentavalent vaccine is responsible for the majority of serious reactions including high fever (>40°C), febrile seizures, hypotonic-hyporesponsive episodes (HHE), and persistent inconsolable screaming. These adverse events led to replacement of wP by acellular pertussis (aP) in many developed countries. In India's Universal Immunization Programme, whole-cell pertussis is still used as it is more immunogenic and cost-effective. The HBV, Hib conjugate, and tetanus toxoid components individually have very low rates of serious adverse events.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.