An imperfect tool: COVID-19 'test & trace' success relies on minimising the impact of false negatives and continuation of physical distancing.
Davis E., Lucas T., Borlase A., Pollington T., Abbott S., Ayabina D., Crellen T., Hellewell J., Pi L., Medley G., Hollingsworth D., Klepac P.
The increasingly evident role of asymptomatic and pre-symptomatic transmission means testing is central to COVID-19 control, but test sensitivity estimates are low (around 65%). We extend an existing branching process contact tracing model, adding diagnostic testing and refining parameter estimates. Poor test sensitivity potentially reduces the efficacy of contact tracing, due to false-negative results impacting quarantine. We show that, counter-intuitively, faster testing could also reduce operational test sensitivity, exacerbating this effect. If sensitivity-based risks are mitigated, we find that contact tracing can facilitate control, but small changes in the population reproduction number (1.3 to 1.5) could impact contact tracing feasibility.