A PHC health worker notices that the freeze indicator (FreezeWatch) in the vaccine carrier has been activated. This indicates that the vaccines may have been damaged by exposure to:
- A Heat above 8°C
- B Light exposure degrading the live virus
- C Moisture contamination of the lyophilized vials
- D Freezing temperatures below 0°C ✓
Correct answer: D. Freezing temperatures below 0°C
Explanation
The FreezeWatch (freeze indicator) is a cold chain monitoring device that alerts when the temperature falls below −0.5°C (freezing point). Certain vaccines — particularly DPT, DT, TT, Hepatitis B, and pentavalent — are highly freeze-sensitive and are destroyed irreversibly by freezing. Live attenuated vaccines (BCG, OPV, MMR) are not freeze-sensitive but are heat-sensitive.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.