Vaccine Vial Monitor (VVM) on a vaccine vial shows the inner square darker than the outer circle. The correct interpretation and action is:

• A Vaccine is potent; administer immediately
• B Vaccine is approaching discard point; use first and reorder
• C Cold chain breach likely; discard only if inner circle is white
• D Vaccine has lost potency; do NOT use ✓

Explanation

On a Vaccine Vial Monitor (VVM), when the inner square is darker than the outer circle, the vaccine has been exposed to excessive heat and has lost potency — it must NOT be used. The stages are: Stage 1 (inner square lighter, usable), Stage 2 (square same color, use soon), Stage 3 (square same or darker — do not use). VVM is a time-temperature indicator that records cumulative heat exposure.

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.