The Vaccine Vial Monitor (VVM) on a multi-dose vial has the inner square darker than the outer circle. The correct action by the health worker is:

• A Use the vaccine immediately — the cold chain has been maintained
• B Discard the vial — heat exposure has exceeded acceptable limits ✓
• C Store the vial at a lower temperature before use
• D Use the vial only if the vaccine appears clear without particulate matter

Explanation

A VVM reading of Stage 3 (inner square as dark as the outer circle) or Stage 4 (inner square darker than outer circle) indicates the heat exposure threshold has been exceeded — the vaccine should NOT be used and must be discarded. In Stages 1 and 2, the inner square is lighter than the outer circle and the vaccine is safe to use. The VVM responds to cumulative heat exposure, not the current storage temperature.

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.