India switched from whole-cell pertussis (wP) to acellular pertussis (aP) component in some combination vaccines. Which feature of wP primarily drove this transition?

• A Lower efficacy of wP against severe disease compared with aP
• B Shorter shelf life of wP in the cold chain
• C Higher reactogenicity of wP, with fever, local reactions and rare hypotonic-hyporesponsive episodes ✓
• D Inability of wP to induce antibodies against pertussis toxin

Explanation

wP contains inactivated whole Bordetella pertussis organisms carrying endotoxin and many bacterial products, causing frequent fever, injection site reactions, and rarely hypotonic-hyporesponsive episodes and convulsions. aP retains efficacy against severe disease and contains purified antigens including inactivated pertussis toxin, FHA, pertactin and fimbriae, so it induces antitoxin antibodies well, ruling out D. wP remains cheaper and highly effective, which is why India's UIP still uses wP in pentavalent schedules where reactogenicity is acceptable.

Reference: Nelson Textbook of Pediatrics, 22nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.