COVID-19 cluster surveillance using exposure data collected from routine contact tracing: The genomic validation of a novel informatics-based approach to outbreak detection in England
Fig 2
COVID-19 incidence and events and exposure clusters reported to contact tracing.
(A) incidence of new confirmed cases; (B) number of events by period of attendance; (C) exposure clusters by event type. Backwards events reflect those reported by cases during the likely exposure period (3–7 days before symptom onset or date of positive test), forwards events those reported after the case was likely infectious (from 2 days before symptom onset or date of positive test to the time of contact tracing). Data is shown relative to national restrictions in England from 23 October 2020 to 1 August 2021. National non pharmaceutical interventions: 1: second national lockdown; 2: third national lockdown; 3–6: roadmap out of restrictions.