Installation Instructions

Page 6 of 9
TM
VOS SYSTEMS LLC
definition. Brief interactions are less likely to result in transmission; however, symptoms and the type of
interaction (e.g., did the infected person cough directly into the face of the exposed individual) remain
important”. < bold added>. The virologists and infectious disease experts with whom we work have
stressed the following:
1. “15 minutes of close exposure” does NOT mean it must be continuous exposure. Context of the
exposure is important.
2. The “type of interaction” is important. For example, 15 periods of 12-minute exposure would
obviously be of more concern than one 15-minute exposure. Again, overall context of the
exposure is important.
3. “Close exposure” should not be precisely defined. For example, 120 minutes of sporadic 7’
exposure would obviously be of more concern than one 15-minute exposure at 5’ (assuming no
one directly coughed on another). Again, context of the exposure is important.
As an example, consider this situation: John, a co-worker with Alice, has tested positive for infection.
Alice has done a good job of socially distancing at work, and over the previous 10-day period Alice has
recorded having no interactions within 6 feet of John, and hence would be considered “low risk” based
on that – not even one instance of over 15 minutes. However, Alice’s work-station sits 8 feet away from
John’s. Alice’s job includes moving often to a nearby work-station (away from John). Even loosening
the range and measuring at a 8-9’ range, because she moves in and out of the area frequently she only
records episodes of a few minutes at a time… no 15-minute episodes. But by doing cumulative
measurement, adding all the short-duration interactions within 8 feet of John, the system shows she has
had a cumulative 36 hours of exposure. Our experts all agree that 36 hours of cumulative indoor
exposure within 7-9 feet would clearly present a much higher risk of infection than would even 15 or 30
minutes of under-6 feet of exposure.
Based on the experts we work with, we recommend choosing range/distance settings that are wider
rather than shorter to produce data that are more statistically valid and helpful. And the example above
demonstrates why we provide “cumulative” data… the system aggregates contact data, including both
shorter and longer periods of duration. Over the long-run of a 10-day or 14-day lookback period, the
“wider” range of distance and aggregation of shorter and longer intervals will provide more actionable
information.