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Vaccine Temperature Buffers: Glycol? Glass Beads? Or What?

The CDC, in its Vaccine Storage and Handling Toolkit for Vaccine and VFC Providers, uses the following language when describing temperature buffers as a necessary edition to a data logger probe: ”Probe in thermal buffer such as glycol . . .”

For Vaccine Providers looking for a data logger, the key part of that sentence is ”such as.” The CDC has yet to fully commit, require, or even recommend a data logger probe be immersed in glycol and glycol only. Here at Dickson, we use glass beads instead of glycol.


Because they offer the same temperature stability as glycol, without as great of a threat of spillage.
This has been a confusing topic as of late, and the verdict isn’t out yet on whether one type of material to immerse your probe in is better than the other. (When the jury decides, we will be sure to let you know.) But, check out the graph below:

One of our excellent engineers thought he would test each solution, to see if there was any variance in temperature readings. So he did. The probes were placed in the same environment, and thus monitored the same temperature. As you can see, we found very little difference between the two solutions. They each followed the exact same curve at the exact same time as the temperatures they monitored rose and fell.

But why submerse a probe into a bottle filled with glass beads or a glycol solution? Because it takes longer for vaccine temperatures to change than it does the air of your refrigerator or freezer. A sensor (that includes internal device sensors!) without an attached glycol bottle or vial of glass beads records the temperature of the atmosphere. Thus, the sensor will show extraneous temperature readings caused by air fluctuations (for example, the opening and closing of a refrigerator door) which may not be indicative of the temperature of the individual vaccines.

So, get yourself a thermal buffer for your data logger. We recommend glass beads, but we can always do glycol as well.