A Vaccine Vial Monitor (VVM) on a DPT vial shows Stage 3, where the inner square is darker than the outer circle. The discard point for VVM is reached when the inner square has reached which color change?
- A Inner square lighter than outer circle
- B Inner square equal to outer circle
- C Inner square darker than outer circle ✓
- D Inner square has reached the same color as the reference ring on the label
Correct answer: C. Inner square darker than outer circle
Explanation
The VVM discard point is reached when the inner square becomes as dark as or darker than the outer circle (Stage 3). At this point, cumulative heat exposure has degraded the vaccine beyond acceptable potency, and the vial must be discarded regardless of the expiry date.
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.