Emerging evidence suggests that contact tracing has had limited success in the UK in reducing the R number across the COVID-19 pandemic. We investigate potential pitfalls and areas for improvement by extending an existing branching process contact tracing model, adding diagnostic testing and refining parameter estimates. Our results demonstrate that reporting and adherence are the most important predictors of programme impact but tracing coverage and speed plus diagnostic sensitivity also play an important role. We conclude that well-implemented contact tracing could bring small but potentially important benefits to controlling and preventing outbreaks, providing up to a 15% reduction in R. We reaffirm that contact tracing is not currently appropriate as the sole control measure.
Bibliographical noteFunding Information: E.L.D., T.C.D.L., A.B., D.A., L.P., T.M.P., G.F.M. & T.D.H. gratefully acknowledge funding of the NTD Modelling Consortium (NTDMC) by the Bill & Melinda Gates Foundation (BMGF) (grant no. OPP1184344). E.L.D., L.P. & T.D.H. gratefully acknowledge funding from the MRC COVID-19 UKRI/DHSC Rapid Response grant MR/V028618/1 and JUNIPER Consortium (MR/V038613/1). The following funding sources are acknowledged as providing funding for the named authors. This research was partly funded by the Bill & Melinda Gates Foundation (NTDMC: OPP1184344: G.F.M.). This project has received funding from the European Union’s Horizon 2020 research and innovation programme - project EpiPose (101003688: P.K.). Royal Society (RP/EA/180004: P.K.). Wellcome Trust (210758/Z/18/Z: J.H., S.A.).
Views, opinions, assumptions or any other information set out in this article should not be attributed to BMGF or any person connected with them. T.C. is funded by a Sir Henry Wellcome Fellowship from the Wellcome Trust (215919/Z/19/Z). T.M.P.’s PhD is supported by the Engineering & Physical Sciences Research Council, Medical Research Council and University of Warwick (EP/L015374/1) and thanks Big Data Institute for hosting him. All funders had no role in the study design, collection, analysis, interpretation of data, writing of the report, or decision to submit the manuscript for publication.
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Publisher Copyright: © 2021, The Author(s).
Citation: Davis, E.L., Lucas, T.C.D., Borlase, A. et al. Contact tracing is an imperfect tool for controlling COVID-19 transmission and relies on population adherence. Nat Commun 12, 5412 (2021).