The ambiguity of "thermometer"
At the turn of the century vaccine fridges were just emerging on the scene. At this time the common way of telling what the fridge temperature was by using a thermometer placed inside the fridge.
The term “thermometer” was clear – it was literally the thermometer that was sitting on the shelf.
With vaccine fridges, however, there is a display of the temperature on the front. Something that displays the current temperature is, by definition, a thermometer.
At the same time, however, the thermometer that was sitting inside the fridge is now replaced by a temperature logger.
This is where Strive For Five failed to move with the times. It still talks about needing to check the accuracy of the thermometer, and even describes the far from reliable “slush test”.
The problem is, the sensor used by the fridge is not easily accessed by the owner, and there is absolutely no way that a slush test can be conducted on it. The temperature logger is also not intended to be submersed in water.
Strive For Five talks about a device that was intended to overcome the shortcomings of a domestic fridge and was made redundant by a temperature logger.
VaxShields does not rely on "thermometers"
VaxShield relies on the built-in temperature sensor of a vaccine fridge (and its display) and the independent temperature logger to monitor the fridge’s temperature.
There is no requirement for a traditional thermometer to be used.
If a thermometer is used, then it needs to have an accuracy of 0.5° or better and it needs to be used in addition to the externally monitored temperature logger.