The Vaccine Vial Monitor (VVM) on a vaccine vial transitions from inner square lighter than outer circle to inner square darker than outer circle. This indicates:

• A The vaccine is approaching discard point — use with caution
• B The vaccine has been adequately frozen and is safe to use
• C The vaccine has reached or exceeded discard point — do not use ✓
• D Cold chain has been maintained throughout — preferred for use

Explanation

When the inner square on a VVM becomes DARKER than or the same color as the outer circle, the vaccine has reached or exceeded the discard point and must NOT be used. VVM stages: Stage 1 — inner square lighter than outer circle (use); Stage 2 — inner square same color as outer circle (use but expedite); Stage 3/4 — inner square darker than outer circle (discard). VVM monitors cumulative heat exposure, not freezing damage — it cannot detect freeze damage for freeze-sensitive vaccines.

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.