The Vaccine Vial Monitor (VVM) on a vaccine vial shows the inner square has become the SAME colour as the outer circle. What action should a health worker take?
- A Discard the vaccine as heat damage has been detected ✓
- B Use the vaccine immediately if within expiry date
- C Return the vaccine to the cold chain equipment for re-cooling
- D Consult the supervisor before using
Correct answer: A. Discard the vaccine as heat damage has been detected
Explanation
When the inner square of the VVM matches (same colour as) or is darker than the outer circle, the vaccine has been irreversibly exposed to unacceptable cumulative heat and must be discarded regardless of expiry date. The VVM uses a heat-sensitive chemical that darkens with heat exposure over time; the endpoint is reached when the square colour equals the circle. If the square is still lighter than the circle, the vaccine is still usable. Re-cooling cannot reverse heat damage already recorded by the VVM.
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.