It is well known that vaccines are temperature sensitive.  They are easily inactivated by exposure to temperatures outside of the standard 2 ^oC to 8 ^oC refrigerated storage range (1, 2).  Both high and low (freezing) temperatures cause inactivation, and recent reports show that inadvertent freezing in the cold chain is a larger problem than heat inactivation.

Temperature loggers, temperature alarms, and VVM (vaccine vial monitors) have historically been used to monitor the vaccine cold chain, and indeed this technology has greatly improved vaccine safety and efficacy worldwide.  Although highly useful, however, this earlier technology has certain drawbacks.  These drawbacks are:

• Temperature loggers must be downloaded and interpreted.  This usually occurs weeks or months after the cold chain break has occurred, and analysis usually takes place far away from the problem area.  Due to distance and time, it is often difficult or impossible to locate the personnel involved in the actual cold-chain break.  As a result, corrective action is slow and difficult, and much vaccine may be lost.

• Temperature alarms that warn on preset values (e.g. freezing or high temperature) are almost impossible to correctly set.  They either warn prematurely or too late, and give information of limited value.  Thus they tend to be disregarded.

• VVM (vaccine vial monitors) do not warn about freezing damage (the most common cause of cold chain failure).  VVM are only available for a few limited vaccine types.  Because VVM rely upon chemical indicators, it is often difficult to precisely tune a VVM to match the stability characteristics of a particular vaccine.  Thus development of a new VVM typically takes several years, and requires the active participation of the vaccine manufacturer.   Since the vaccine label is changed, use of a VVM may require additional regulatory review. Many manufacturers have been slow or reluctant to implement VVMs.

The ideal vaccine monitor?

The ideal vaccine monitor might have the following characteristics:

• Instantly warn when the cold chain breaks (relative to a particular vaccine's stability)
• Detect all cold chain problems, not just elevated temperature
• Accurately report vaccine stability - report real problems, not just false alarms
• Log (record) temperatures before and after the cold chain break (for later analysis)
• Be instantly customized to a particular vaccine's time-temperature stability curve
• Not require large amounts of manufacturer's time and expense
• Be capable of being implemented without additional manufacturer effort
• Not require large amounts of regulatory review
• Be easy to validate
• Be simple, quick, and easy to implement

Consider the LifeTrack 

The LifeTrack has all the features of the "ideal" vaccine monitor listed above.  Essentially the device combines the best features of a temperature logger, temperature alarm, and VVM into a new type of device that brings vaccine cold chain monitoring to a higher level of flexibility, precision, and control.  See our publication in Vaccine.   

Packaging the LifeTrack

Ideally one LifeTrack unit is packaged per carton of vaccine vials.  The unit should be attached to the carton by a moderately strong adhesive, or as a subsection of the carton, so that the linkage between the LifeTrack unit and the vaccine vials is maintained throughout the cold chain.  The LifeTrack unit should be added to the vaccine carton as soon as possible after manufacturing, and should be left with the carton until all the vaccine vials have been used. 

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