4.2. URTI Episodes
common-cold
SEPARATION, EVENT
We also made an attempt to assess the number of URTI episodes over the entire trial period. However, this parameter was found to be of limited value, mainly due to the necessity of manipulating the raw data in order to manually enumerate the episodes, as well as the challenge of accurately defining URTI episodes. For the purpose of this analysis, we defined the most probable episodes as being those of the second severity level (mediocre symptoms) and lasting for at least 3 days, with 3 days of separation from another event. The difficulty with this approach was that many symptomatic days could not be included in the identifiable episodes. In some instances, they were not part of a ≥3-day-long sequence or, in other cases, the separation of such sequences was not long enough (<3 days). The latter case was the main problem when we initially attempted to count episodes of all severity levels, including those with the mildest symptoms. The symptoms of the first gravity level were sometimes reported over long periods without a 3-day separation between them, thus making it impossible to accurately calculate the individual URTI episodes of all severity levels.Another problem with enumerating the URTI episodes is that the old definition of the common-cold event seems to be currently less practical. The classical description of such an event was that it typically lasted for about 7 days and appeared with mild-to-moderate symptoms [