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Review
. 2021 May;27(5):1301-1308.
doi: 10.3201/eid2705.204876.

Epidemiologic Findings from Case Investigations and Contact Tracing for First 200 Cases of Coronavirus Disease, Santa Clara County, California, USA

Nancy Ortiz, Elsa Villarino, James T Lee, Kristina L Bajema, Jessica N Ricaldi, Shanon Smith, Wen Lin, Margaret Cortese, Albert E Barskey, Juliana F Da Silva, Brandon J Bonin, Sarah Rudman, George S Han, Marc Fischer, Shua J Chai, Sara H Cody; Santa Clara County COVID-19 Case Investigation Team
Collaborators
Review

Epidemiologic Findings from Case Investigations and Contact Tracing for First 200 Cases of Coronavirus Disease, Santa Clara County, California, USA

Nancy Ortiz et al. Emerg Infect Dis. 2021 May.

Abstract

In January 2020, Santa Clara County, California, USA, began identifying laboratory-confirmed coronavirus disease among residents. County staff conducted case and contact investigations focused on households and collected detailed case demographic, occupation, exposure, and outcome information. We describe the first 200 test-positive cases during January 31-March 20, 2020, to inform future case and contact investigations. Probable infection sources included community transmission (104 cases), known close contact with a confirmed case-patient (66 cases), and travel (30 cases). Disease patterns across race and ethnicity, occupational, and household factors suggested multiple infection risk factors. Disproportionately high percentages of case-patients from racial and ethnic subgroups worked outside the home (Hispanic [86%] and Filipino [100%]); household transmission was more common among persons from Vietnam (53%). Even with the few initial cases, detailed case and contact investigations of household contacts capturing occupational and disaggregated race and ethnicity data helped identify at-risk groups and focused solutions for disease control.

Keywords: COVID-19; California; SARS-CoV-2; coronavirus disease; epidemiology; respiratory infections; severe acute respiratory syndrome coronavirus 2; viruses; zoonoses.

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Figures

Figure 1
Figure 1
Week of symptom onset, for first 200 confirmed coronavirus disease cases, by exposure source, Santa Clara County, California, USA, January 31–March 20, 2020.
Figure 2
Figure 2
Hospitalization status and outcomes, for first 200 confirmed coronavirus disease cases, by age group, Santa Clara County, California, USA, January 31–March 20, 2020. Outcomes are classified by most severe status at time of case investigation. Deaths are as of May 20, 2020. ICU, intensive-care unit.
Figure 3
Figure 3
Geographic location of first 200 confirmed coronavirus disease cases, by case-patient’s ZIP code area of residence (for those areas with >2,000 residents), Santa Clara County, California, USA, January 31–March 20, 2020. A) No. cases; B) case rate (cases/100,000 population).
See this image and copyright information in PMC

References

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