Speed, compliance and monitoring crucial to test and trace programmes

Test, trace and isolate programmes could help control the spread of COVID-19 if test results are delivered quickly, contacts are traced and public compliance is high, finds a report co-authored by UCL's Professor Dame Anne Johnson. The findings were released today by the Data Evaluation and Learning for Viral Epidemics (DELVE) group, a multi-disciplinary team convened by the Royal Society to support a data-driven approach to learning from the different approaches countries are taking to managing the pandemic. They highlight that the speed at which fast tests can be completed, results delivered and contact traced, high levels of public compliance and the ability to identify a large proportion of cases will be crucial to the success of any Test, Trace and Isolate (TTI) programme. Research by DELVE shows that, if effectively implemented across the population, TTI can help control the UK COVID-19 epidemic as part of a wider package of interventions including distancing, infection control, and hand and respiratory hygiene. Self-isolation of symptomatic individuals and quarantine of their household contacts as part of the TTI system, has a substantial impact on the number of new infections generated by each index case. Adding contact tracing for extra-household contacts of confirmed cases to this broader package of interventions reduces the number of new infections otherwise occurring by 5-15%. DELVE modelling shows that the upper end of this range can be achieved when the overall test and trace period for contacts has been reduced from five days to three days, due to the quarantining of infected contacts just before they become most infectious.