Effective contact tracing for COVID-19: A systematic review
Carl-Étienne Juneau, Anne-Sara Briand, Pablo Collazzo, Uwe Siebert, Tomas Pueyo · Global Epidemiology · 2023
= 18) provided consistent, high-certainty evidence that under assumptions of prompt and thorough tracing with effective quarantines, contact tracing could stop the spread of COVID-19 (e.g. by reducing the reproduction number from 2.2 to 0.57). A cautious interpretation indicates that to stop the spread of COVID-19, public health practitioners have 2-3 days from the time a new case develops symptoms to isolate the case and quarantine at least 80% of its contacts.