The Full Form of VVM is‍ Vaccine vial monitor.

A vaccine vial monitor (VVM) is a thermochromic label put on vials containing vaccines which gives a visual indication of whether the vaccine has been kept at a temperature which preserves its potency. The labels were designed in response to the problem of delivering vaccines to developing countries where the cold chain is difficult to preserve, and where formerly vaccines were being rendered inactive and administered ineffectively due to their having been denatured by exposure to ambient temperature.