A Vaccine Vial Monitor (VVM) on a pentavalent vial shows the inner square darker than the outer circle. The correct action for the health worker is:

• A Use the vaccine immediately, as the VVM confirms cold chain integrity
• B Shake the vial vigorously and reassess the VVM reading after 30 minutes
• C Do NOT use the vaccine; discard it ✓
• D Use it for older children >5 years only, as potency may be partially retained

Explanation

When the inner square of the VVM is DARKER than or the same color as the outer circle (VVM reading Stage 3 or 4), the vaccine has been exposed to excessive cumulative heat and must NOT be used — discard it regardless of expiry date. When the inner square is lighter than the outer circle, the vaccine is suitable for use. Shaking or partial use does not restore potency. The VVM is an irreversible time-temperature indicator; its change reflects cumulative heat exposure damage to the immunogen.

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.