The story of a time and temperature indicator that has dramatically changed the course of vaccine
management practices as well as shaped the future of the cold chain.


Here is a fun game for you.

VVMs can help in deciding which vials are to be dispatched first from storage facilities. Similarly, VVMs help health workers to decide which ones to use first for different types of activities. Vaccines can be safely used when the inner square of VVM is lighter than the outer circle (reference). When there are different shades of inner square of VVM (still lighter than the outer circle), in principle the darker one should be used first. However, there are cases where lighter VVMs should be picked up and not the darker ones. Let’s review different situations and reasons for using light or dark VVMs.

Let’s assume that on day 12 May 2020, we have the following OPV vials in the health centre refrigerator. Your challenge is to decide which OPV vial to use first for each of the three scenarios given below. Simply drag the VVM card of your choice in the table below. As for the “next pick” consider if the contents of your first pick vial has finished and you still need to vaccinate children. When you make a mistake, all cards will be shuffled again.

Fixed immunization session at the health centre

Opened vials must be used first for fixed immunization sessions.
If an open vial is finished in the session and you still have children to be immunized, next pick would be the darkest VVM with OPV#3.

Short outreach – Departing from the health centre, conducting the outreach session and come back is within 4 hours

In principle, open vials must be used first. However, in order to reduce the contamination risk, they should be used by caution for outreach.
Depending on how many doses are remaining in the opened vial, next pick would be the darkest VVM with OPV #3.

Long outreach - Departing from the health centre, conducting the outreach session and come back is 48 hours

It is not correct to risk VVMs reaching to their discard point in long outreach activities. This is why we do not recommend vaccines with darkest VVMs to be used. Best is to pick a VVM that still has quite a safety margin – a lighter one. Here in our example, we have 2 VVMs that are lighter than the OPV #3, one with expiry date 08.2020 with a darker one, and the other much lighter with 10.2020 expiry. Depending on the climatic conditions, picking any of these two would be correct.