Modeling the Comparative Impact of Individual Quarantine vs. Active Monitoring of Contacts for the Mitigation of COVID-19

Corey M Peak; Rebecca Kahn; Yonatan H Grad; Lauren M Childs; Ruoran Li; Marc Lipsitch; Caroline O Buckee

The number of days an individual is under quarantine or active monitoring is measured as the time difference between when an individual is identified via contact tracing and when symptoms prompt isolation -which is immediate for an individual under quarantine and determined by the frequency of monitoring for an individual under active monitoring. We assume individuals under active monitoring or quarantine who are uninfected are followed for a duration of 14 days until clearance, consistent with recent interventions. 13 We calculated the expected percentage of infections that result from presymptomatic infectiousness in the absence of interventions as the sum total of expected secondary cases caused by an individual prior to symptom onset divided by the total force of infection for that individual times 100. This percentage equals 0% when symptom onset precedes infectiousness and equals 100% when the entire duration of infectiousness concludes prior to symptom onset.