Engagement and adherence trade-offs for SARS-CoV-2 contact tracing

• Published in: Philosophical transactions of the Royal Society of London. Series B. Biological sciences Vol. 376; no. 1829; p. 20200270
• Main Authors: Lucas, Tim C D, Davis, Emma L, Ayabina, Diepreye, Borlase, Anna, Crellen, Thomas, Pi, Li, Medley, Graham F, Yardley, Lucy, Klepac, Petra, Gog, Julia, Déirdre Hollingsworth, T
• Format: Journal Article
• Language: English
• Published: England The Royal Society 19.07.2021
• Subjects: Basic Reproduction Number - statistics & numerical data; Communicable Disease Control - statistics & numerical data; Contact Tracing - statistics & numerical data; COVID-19 - epidemiology; COVID-19 - transmission; COVID-19 - virology; Disease Outbreaks; Humans; Models, Theoretical; Pandemics; SARS-CoV-2 - pathogenicity; COVID-19; SARS-CoV-2; quarantine; case isolation; contact tracing; adherence
• ISSN: 0962-8436; 1471-2970; 1471-2970
• DOI: 10.1098/rstb.2020.0270

Contact tracing is an important tool for allowing countries to ease lockdown policies introduced to combat SARS-CoV-2. For contact tracing to be effective, those with symptoms must self-report themselves while their contacts must self-isolate when asked. However, policies such as legal enforcement of self-isolation can create trade-offs by dissuading individuals from self-reporting. We use an existing branching process model to examine which aspects of contact tracing adherence should be prioritized. We consider an inverse relationship between self-isolation adherence and self-reporting engagement, assuming that increasingly strict self-isolation policies will result in fewer individuals self-reporting to the programme. We find that policies which increase the average duration of self-isolation, or that increase the probability that people self-isolate at all, at the expense of reduced self-reporting rate, will not decrease the risk of a large outbreak and may increase the risk, depending on the strength of the trade-off. These results suggest that policies to increase self-isolation adherence should be implemented carefully. Policies that increase self-isolation adherence at the cost of self-reporting rates should be avoided. This article is part of the theme issue 'Modelling that shaped the early COVID-19 pandemic response in the UK'.