Case Investigation and Contact Tracing Efforts From Health Departments in the United States, November 2020 to December 2021.

BACKGROUND: Sixty-four state, local, and territorial health departments (HDs) in the United States report monthly performance metrics on coronavirus disease 2019 (COVID-19) case investigation and contact tracing (CI/CT) activities. We describe national CI/CT efforts from 25 October 2020 through 24 December 2021, which included 3 peaks in COVID-19 case reporting. METHODS: Standardized CI/CT data elements submitted by the 64 HDs were summarized as monthly performance metrics for each HD and the nation. These included measures of CI/CT completeness, timeliness, and workloads. We calculated contact tracing efficacy as the proportion of new cases that occurred in persons identified as contacts within the 14 days before the case was reported. RESULTS: A total of 44 309 796 COVID-19 cases were reported to HDs, with completed HD interviews in 18 153 353 (41%). Less than half of interviews yielded ≥1 contact. A total of 19 939 376 contacts were identified; 11 632 613 were notified (58%), with 3 618 846 undergoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing within 14 days of notification. Of the total reported cases, 2 559 383 occurred in recently identified contacts. CONCLUSIONS: We document the resource-intense nationwide effort by US HDs to mitigate the impact of COVID-19 through CI/CT before and after vaccines became widely available. These results document the coverage and performance of CI/CT despite case surges and fluctuating workforce and workloads.

COVID-19 Case Investigation and Contact Tracing Efforts from Health Departments - United States, June 25-July 24, 2020.

Case investigation and contact tracing are core public health tools used to interrupt transmission of pathogens, including SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19); timeliness is critical to effectiveness (1,2). In May 2020, CDC funded* 64 state, local, and territorial health departments† to support COVID-19 response activities. As part of the monitoring process, case investigation and contact tracing metrics for June 25-July 24, 2020, were submitted to CDC by 62 health departments. Descriptive analyses of case investigation and contact tracing load, timeliness, and yield (i.e., the number of contacts elicited divided by the number of patients prioritized for interview) were performed. A median of 57% of patients were interviewed within 24 hours of report of the case to a health department (interquartile range [IQR] = 27%-82%); a median of 1.15 contacts were identified per patient prioritized for interview§ (IQR = 0.62-1.76), and a median of 55% of contacts were notified within 24 hours of identification by a patient (IQR = 32%-79%). With higher caseloads, the percentage of patients interviewed within 24 hours of case report was lower (Spearman coefficient = -0.68), and the number of contacts identified per patient prioritized for interview also decreased (Spearman coefficient = -0.60). The capacity to conduct timely contact tracing varied among health departments, largely driven by investigators' caseloads. Incomplete identification of contacts affects the ability to reduce transmission of SARS-CoV-2. Enhanced staffing capacity and ability and improved community engagement could lead to more timely interviews and identification of more contacts.