When the severity of a temperature excursion also depends on its duration, the WarmMark single-use, ascending time temperature indicator is the best choice. With this temperature indicator, you can see not only whether a temperature excursion occurred, but whether it was extended, brief or of a moderate time period, and thus determine whether vaccine safety or efficacy has deteriorated. For a demonstration of the WarmMark time-temp indicator and how it works, please watch this short video.