Fig. 4: Association of clustered red alerts with symptom progression.
From: Real-time alerting system for COVID-19 and other stress events using wearable data
a, Bubble plot showing day-by-day frequency counts of individuals reporting symptoms during the second half of the infection detection window (from symptom onset to 21 d later). Bubble size and shading are indicative of the relative magnitude of the frequency count and the median severity, respectively. The percentage in the brackets alongside each symptom indicates the total number of individuals reporting that symptom over all 21 d as a fraction of the total number of symptomatic participants who tested positive for SARS-CoV-2. b, Illustrative example tracing the symptoms of a participant who tested positive for SARS-CoV-2 from symptom onset to 21 d later and continuing thereafter intermittently for an additional 2 months. For each day, an aggregate symptom score was computed as the sum of the relative severity of the symptoms, each weighted by its specificity to individuals who tested positive for SARS-CoV-2. The scale for computing the symptom score was based on individual symptom intensities, each ranging from mild (score = 1) to very severe (score = 5) as reported by the participant. The aggregated score shown in this bar plot is a measure of the overall severity. c, The bar plots show the percentages of red alert periods (from NightSignal algorithm) associated with each symptom (left) or activity (right) as annotated by participants who tested positive for COVID-19 as well as by participants who tested negative for COVID-19.
