What is it about?

Testing, contact tracing, and isolating or quarantining is a key strategy for reducing transmission of infectious diseases, including COVID-19. But traditional contact tracing takes time and requires a trained workforce. Limited contact tracing capacity can become overwhelmed as cases rise. Our aim was to quantify the relationship between contact tracing capacity and transmission of SARS-CoV-2, as measured by the reproductive number, Rt, over the course of an epidemic. We also examined how delays in testing or contact tracing and variation among individuals in transmission influenced epidemic outcomes.

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Why is it important?

This manuscript could be used to plan and allocate contact tracing resources for the next emerging infectious disease. Sufficient contact tracing capacity and quick and widely available testing could stop an epidemic before it becomes widespread. In contrast, we found that if contact tracing capacity is insufficient, epidemics will accelerate until either behavioral change or immunity limit them, as we saw for COVID-19.


Public health often sees boom-bust cycles of funding, and the cutting of public health budgets in the last year is evidence of that pattern repeating. I hope we have learned from the COVID-19 pandemic and allocate sufficient resources to maximize our chance of controlling the next emerging disease.

A. Marm Kilpatrick
University of California Santa Cruz

Read the Original

This page is a summary of: Contact tracing efficiency, transmission heterogeneity, and accelerating COVID-19 epidemics, PLoS Computational Biology, June 2021, PLOS,
DOI: 10.1371/journal.pcbi.1009122.
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