During cold chain monitoring, a freeze indicator in a vaccine box has been triggered. The concerned vaccine that is MOST damaged by freezing is:

• A Oral polio vaccine (OPV)
• B Measles-rubella (MR) vaccine
• C Diphtheria-Tetanus-Pertussis (DTP) whole-cell vaccine ✓
• D BCG vaccine

Explanation

DTP (whole-cell), hepatitis B, Hib, and liquid pentavalent vaccines are freeze-sensitive — freezing causes irreversible aggregation of aluminium adjuvant-antigen complexes, reducing potency significantly. In contrast, OPV, MR, and BCG are freeze-tolerant vaccines that can withstand freezing without damage. The shake test is used to detect freeze damage in adsorbed vaccines (those containing alum): a frozen-thawed vaccine forms floccular precipitate that does not resuspend, unlike the intact vaccine which shows uniform suspension.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.