Abstract: Described in some aspects of the present invention are methods and systems that can be used to track occurrences and/or non-occurrences of medical-related events, for example, to record whether one or more medical-related events have occurred at a particular time or during a particular time interval. Any suitable number of events may be tracked using such methods and systems, and the types and varieties of events that can be tracked are diverse. Examples include but are not limited to vaccine or other drug administrations, physical therapies, tests, diagnoses and surgeries. In some preferred embodiments, these and/or other medical-related occurrences or events will be tracked using an article that can be worn about the body of a patient although a variety of non-wearable articles can be utilized as well.