A Multifaceted Evaluation of a COVID-19 Contact Tracing Program in King County, Washington

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J Public health management practice. 2022 Jul-Aug 01;28(4):334-343. doi: 10.1097/PHH.0000000000001541.


BACKGROUND: Despite the massive scale of COVID-19 case investigation and contact tracing (IC/CT) programs operating around the world, evidence supporting the impact of the intervention on the public health are limited.

OBJECTIVE: To evaluate the CI/CT program of Public Health-Seattle & King County (PHSKC), including its reach, timeliness, effect on compliance with isolation and quarantine (I&Q), and potential for mitigation difficulties related to the pandemic.

DESIGN: This program evaluation used descriptive statistics to analyze surveillance records, case and contact interviews, referral records, and investigation data provided by a sample of cases who had recently terminated isolation.

BACKGROUND: PHSKC is one of the largest local government health departments in the United States. It serves more than 2.2 million people who reside in Seattle and 38 other municipalities.

PARTICIPANTS: Residents of King County who were diagnosed with COVID-19 between July 2020 and June 2021.

INTERVENTION: PHSKC has integrated COVID-19 IC/CT into prevention education and service delivery.

RESULTS: The PHSKC CI/CT team interviewed 42,900 cases (82% of cases eligible for CI/CT), an average of 6.1 days after symptom onset and 3.4 days after testing for SARS- CoV-2. The cases revealed the names and addresses of 10,817 unique workplaces (mean = 0.8/interview) and 11,432 other recently visited locations (mean = 0.5/interview) and provided contact information for 62,987 members of the household (mean = 2.7/interview) and 14,398 non-household contacts (mean = 0.3/interview). The CI/CT team helped arrange COVID-19 testing for 5,650 contacts, facilitated grocery delivery for 7,253 households, and referred 9,127 households for financial assistance. I&Q exit survey participants (n=304, 54% of sample) reported self-notifying an average of 4 non-household contacts and 69% agreed that the information and referrals provided by the IC/CT team had helped them stay isolated.

CONCLUSIONS: During the 12-month evaluation period, CI/CT reached 42,611 households and identified thousands of exposure locations. Timing of IC/CT relative to infectiousness and difficulty in obtaining non-household contacts may have mitigated the effect of the intervention. Through the promotion of I&Q advice and services, CI/CT can help alleviate the difficulties associated with the pandemic.

PMID:35616571 | DOI:10.1097/PHH.0000000000001541