Vaccine vial monitors (VVMs) track cumulative heat exposure. A vial with VVM stage 3 (inner square darker than outer circle but same shade) is:

• A Safe to use immediately
• B Discarded — vaccine quality is suspect
• C To be used first — indicates it is at the discard point ✓
• D Valid for 28 days if stored at 2–8°C

Explanation

VVM has four stages: Stage 1 (inner square lighter) = fine; Stage 2 (inner square beginning to darken but still lighter) = use soonest; Stage 3 (inner square same shade as outer circle) = use caution, vaccine approaching end of usable life, use first; Stage 4 (inner square darker) = discard. At Stage 3, the vaccine can still be used but must be prioritized.

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.