WHO has just released a new infographic that summarises how health workers can use vaccine vial monitors (VVMs) to decide whether or not to use a vaccine vial. Most notably, it presents VVM colour change as a continuous progression, rather than as four distinct stages A VVM is a chemical indicator label attached to the vaccine container (vial, ampoule or dropper) by the vaccine manufacturer. As the container moves through the supply chain, the VVM records its cumulative heat exposure through a gradual change in colour.
If the colour of the inner square is the same colour or darker than the outer circle, the vaccine has been exposed to too much heat and should be discarded. The main purpose of VVMs is to ensure that heat-damaged vaccines are not administered. The VVM status is also used to decide which vaccines can safely be kept after a cold chain break occurs thus minimizing…
