Coronavirus Disease Contact Tracing Outcomes and Cost, Salt Lake County, Utah, USA, March–May 2020

Victoria L. Fields; Ian T. Kracalik; Christina Carthel; Adriana Lopez; Amy Schwartz; Nathaniel M. Lewis; Mackenzie Bray; Carlene Claflin; Kilee Jorgensen; Ha Khong, Walter Richards; Ilene Risk; Maureen Smithee; Madison Clawson; Lee Cherie Booth; Tara Scribellito; Jason Lowry; Jessica Huynh; Linda Davis; Holly Birch; Tiffany Tran; Joseph Walker; Alicia Fry; Aron Hall; Jodee Baker; Eric Pevzner; Angela C. Dunn; Jacqueline E. Tate; Hannah L. Kirking; Tair Kiphibane; Cuc H. Tran


Emerging Infectious Diseases. 2021;27(12):2999-3008. 

In This Article

Abstract and Introduction


Outcomes and costs of coronavirus disease (COVID-19) contact tracing are limited. During March–May 2020, we constructed transmission chains from 184 index cases and 1,499 contacts in Salt Lake County, Utah, USA, to assess outcomes and estimate staff time and salaries. We estimated 1,102 staff hours and $29,234 spent investigating index cases and contacts. Among contacts, 374 (25%) had COVID-19; secondary case detection rate was ≈31% among first-generation contacts, ≈16% among second- and third-generation contacts, and ≈12% among fourth-, fifth-, and sixth-generation contacts. At initial interview, 51% (187/370) of contacts were COVID-19–positive; 35% (98/277) became positive during 14-day quarantine. Median time from symptom onset to investigation was 7 days for index cases and 4 days for first-generation contacts. Contact tracing reduced the number of cases between contact generations and time between symptom onset and investigation but required substantial resources. Our findings can help jurisdictions allocate resources for contact tracing.


By July 2021, >33 million cases of coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), were documented in the United States, and most cases involved contact tracing by health departments.[1] Preventing SARS-CoV-2 transmission through contact tracing requires rapid diagnosis, immediate isolation of cases, and rigorous tracking and precautionary isolation of close contacts.[2–4] Because SARS-CoV-2 appears to be most transmissible before and immediately after symptom onset, clinical and transmission studies have shown that timely identification of cases and contacts is essential to preventing transmission.[5–7] In addition, mathematical models have shown contact tracing, when implemented with other mitigation measures, can effectively reduce community spread of SARS-CoV-2.[8,9]

Evaluations of contact tracing for tuberculosis and HIV have found that contact tracing is an effective and sustainable approach to transmission reduction when disease prevalence is low but that contact tracing becomes less cost-effective as disease prevalence increases compared with other approaches, such as provider-initiated testing and intensified case finding.[10,11] Programmatic data on outcomes and costs of contact tracing for COVID-19 are limited but essential for aiding public health agencies in designing or improving existing contact tracing programs.[12] We aimed to quantify contact tracing efforts in Salt Lake County, Utah, USA, to examine how contact tracing affected case-finding, evaluate key contact tracing time intervals, and estimate the staff time and salary costs required to conduct investigations.