Abstract
Objective:
Case investigation and contact tracing (CI/CT) are fundamental public health efforts widely used during the COVID-19 pandemic to mitigate transmission. This study investigated how state, local, and tribal public health departments used CI/CT during the COVID-19 pandemic, including CI/CT methodology, staffing models, training and support, and efforts to identify or prioritize populations disproportionately affected by COVID-19.
Methods:
During March and April 2022, we conducted key informant interviews with up to 3 public health officials from 43 state, local, and tribal public health departments. From audio-recorded and transcribed interviews, we used the framework method to analyze key themes.
Results:
Major adjustments to CI/CT protocols during the pandemic included (1) prioritizing populations for outreach; (2) implementing automated outreach for nonprioritized groups, particularly during COVID-19 surges; (3) discontinuing contact tracing and focusing exclusively on case investigation; and (4) adding innovations to provide additional support. Key informants also discussed the utility of having backup staffing to support overwhelmed public health departments and spoke to the difficulty in “right-sizing” the public health workforce, with COVID-19 surges leaving public health departments understaffed as case rates rose and overstaffed as case rates fell.
Conclusions:
When addressing future epidemics or outbreaks, public health officials should consider strategies that improve the effectiveness of CI/CT efforts over time, such as prioritizing populations based on disproportionate risk, implementing automated outreach, developing models that provide flexible additional staffing resources as cases rise and fall among local public health departments, incorporating demographic data in laboratory reporting, providing community connections and support, and having a system of self-notification of contacts.
Case investigation and contact tracing (CI/CT) are fundamental public health efforts that reduce infectious disease transmission and outbreaks by identifying and contacting people who have been infected with or exposed to a communicable disease. 1 Case investigation involves supporting people who have been infected, providing isolation recommendations, educating people on treatment if appropriate, and asking people about their contacts during the infectious period. Contact tracing involves notifying people possibly exposed to infectious disease and providing quarantine, testing, and treatment recommendations. 2 Although CI/CT is used for >120 infectious diseases, CI/CT for COVID-19 presented unprecedented challenges to the US public health infrastructure at state, tribal, local, and territorial levels because of the number of people infected, the speed of transmission, and the complexity of encouraging behavior change—particularly given health, economic, and information disparities.3-6 Public health departments also had challenges in the implementation of CI/CT during the COVID-19 pandemic because outbreak cycles required rapid expansion of the public health workforce and because levels of public participation in public health response and mitigation efforts varied as the pandemic progressed. 7
The Centers for Disease Control and Prevention (CDC) partnered with Mathematica and the National Academy for State Health Policy to conduct a multiphase project evaluating the implementation and evolution of CI/CT during the COVID-19 pandemic. This analysis focused on the actions that public health agencies used to address COVID-19 at state, local, and tribal levels.
Methods
Participants and Data Collection
We conducted key informant interviews in March and April 2022 with public health officials from 20 state, 21 local, and 2 tribal public health departments. To ensure diversity in representation, we recruited states that varied in geographic location, governance, COVID-19 case rates, and social vulnerability, 8 and we conducted a principal components analysis of all states that met a minimum threshold of data completeness in COVID-19 data submitted to CDC during the pandemic. We used results from the principal components analysis to select states for recruitment (eSupplement).
Many public health departments experienced changes in staffing and leadership during the pandemic; thus, to minimize gaps in knowledge among key informants, we invited up to 3 key informants to participate in all interviews. At the state level, we asked state epidemiologists to identify key informants involved in leading CI/CT in their state. To integrate local perspectives, we also asked state epidemiologists to recommend a local public health department with sufficient staffing and capacity to speak about their experiences with CI/CT. All but 2 states, which operate in a structure without local public health departments, recommended local public health departments.
We selected 5 cities to represent large city public health departments operating autonomously or semiautonomously from their state public health department. We selected 2 sites from a tribal nation that participated in a previous study on COVID-19 contact tracing and that operate autonomously. 9 Across all public health departments, we interviewed 114 respondents across 43 group interviews using a structured interview guide (eSupplement); participation was voluntary, and interviews lasted approximately 60 minutes. With respondents’ verbal consent, we recorded and transcribed all interviews.
Disease trends and guidance from public health agencies, including CDC, affected CI/CT implementation by public health departments. We referenced data from CDC’s COVID Data Tracker, which shows COVID-19 data including cases and new hospital admissions and can illustrate surges in admissions following periods of high disease transmission in the community. For our analyses, we included the surge from November 2020 through February 2021, the surge from August through October 2021, and the surge from December 2021 through February 2022. 10 In November 2020, CDC released initial CI/CT prioritization guidance that recommended prioritizing people diagnosed with COVID-19 who had recent laboratory results. 11
This study was reviewed by CDC and deemed not to be research as defined in 45 CFR 46.102(l) (US Department of Health and Human Services, Title 45 Code of Federal Regulations 46, protection of human subjects).
Data Analysis
We analyzed transcripts in NVivo qualitative software release 1.0 (Lumivero) by using a code list developed from our research questions and preliminary themes that emerged during interviews. Four team members (C.S., R.H., R.G., E.R.S.) completed coding for all interviews. The lead author (C.S.) reviewed the first round of interview transcripts coded by each team member, and the team met to discuss and resolve any discrepancies in the coders’ understanding of the codes. The lead author performed quality assurance checks of each coder’s work. After completion of coding, the team developed analytic summaries of coded text based on each key topic in the code list by using the framework method. 12
Results
Initial CI/CT Approaches for COVID-19 Among Public Health Departments
Some states used centralized models, with CI/CT efforts led primarily at the state level; other states used decentralized models in which local public health departments had primary responsibility. Many states used a mix of centralized and decentralized approaches, with the state and local public health departments leading different aspects of the CI/CT effort (Table 1). The models used for CI/CT did not always align with the states’ public health models used for other diseases before the pandemic. For example, a state public health department in the Midwest with a decentralized public health system developed a centralized system for CI/CT. The state officials felt that keeping operations at the state level would provide better support and resources, “especially for the smaller local health departments,” while allowing a few large local public health departments to operate semiautonomously. This hybrid approach, in which states supported small and rural communities and allowed large urban jurisdictions to implement their own CI/CT, was common.
Characteristics of study sites in a review of case investigation and contact tracing (CI/CT) during the COVID-19 pandemic in the United States, as of April 2022
Abbreviation: SVI, Social Vulnerability Index.
Data source: US Census Bureau. 13
In centralized approaches, state public health departments (PHDs) led the CI/CT efforts. In decentralized approaches, local PHDs (eg, city, county) led the CI/CT efforts, with some state support. “Both” indicates that both state and local entities contributed staff and leadership to CI/CT efforts. 14
Comorbidity is defined as the county-level prevalence of any of 5 medical conditions associated with risk of severe COVID-19 illness (obesity, heart disease, chronic obstructive pulmonary disease, diabetes, and chronic kidney disease) 15 ; a weighted average was calculated for states. SVI is defined as the county-level Social Vulnerability Index 8 ranking (high rankings denote greater social vulnerability); a weighted average was calculated for states. More information on how this variable was calculated can be found in the eSupplement.
In a centralized or largely centralized structure, local PHDs are primarily led by employees of the state. In decentralized or largely decentralized structures, local PHDs are primarily led by employees of local governments. In mixed structures, some local PHDs are led by employees of the state and some are led by employees of local government; no single structure predominates. In shared or largely shared structures, local PHDs might be led by employees of the state or by employees of local government. If they are led by state employees, then local government has the authority to make fiscal decisions and/or issue public health orders; if they are led by local employees, then the state has authority. 16
The state PHD used a decentralized approach to CI/CT at the time of site selection in December 2021 but switched to a centralized approach in January 2022.
The state PHD initially used a centralized approach to CI/CT but shifted to a decentralized approach in September 2021.
The most common outreach method used by public health departments early in the pandemic, when other interventions were unavailable or had uncertain efficacy, was calling all people with positive COVID-19 test results and people known to be exposed to COVID-19 (ie, contacts). A state public health department in the West noted that, in the beginning, “everything was about the manual call.” Public health departments described the CI/CT calls during this period as “very intensive,” and some noted that, in addition to calling contacts, they also called places where people who tested positive for COVID-19 had been, such as businesses, churches, or schools. These initial efforts, focused on stopping the spread of COVID-19 in the community, necessitated working 7 days a week to complete calls. Most public health departments developed their initial interview scripts in-house by adapting questions used to investigate other communicable diseases, such as sexually transmitted infections and HIV.
Changes in CI/CT Approaches During the Pandemic Among Public Health Departments
As COVID-19 case counts increased, states often initiated and funded call centers that were largely staffed by contract workers; counties adopted these systems and began using them on an ongoing basis. Over time, more counties opted into these systems as they gained confidence in the contractors’ abilities to conduct interviews with people with positive COVID-19 test results. Several states used models in which counties could alternate between taking on the full caseload of CI/CT calls, when the number of cases was manageable, and assigning some CI/CT calls to the state, when the number of cases exceeded local capacity. In some states, small local public health departments took advantage of this support from the state, whereas large local public health departments, which had more resources than small departments to do their own CI/CT, operated semiautonomously.
Local public health departments described state call centers as helpful but noted as a downside that some call center staff were unfamiliar with the local community. A local public health department in the Northeast noted: [The state call center] was a huge, very much needed resource because locals could not handle the number of cases, but [we] also lost that local connectivity in the community and being able to really focus on the clusters and support those cases.
As the pandemic progressed, states also developed customized data systems generally using 1 of 2 approaches: (1) hiring a contractor to develop a customized database in a software platform or (2) using the state’s existing infectious disease surveillance system with some modifications for COVID-19.
Throughout the pandemic, as information about health risks grew and case rates varied, public health departments adjusted their CI/CT methodology, including (1) prioritizing certain populations for CI/CT outreach from live callers; (2) implementing automated outreach for nonprioritized groups, particularly during surges; (3) stopping contact tracing and focusing exclusively on case investigation; and (4) adding innovations to provide additional support. The first 3 of these changes generally occurred in response to surges, when public health departments realized it was no longer feasible to call all people diagnosed with COVID-19 and their contacts. During the November 2020 through February 2021 surge, many public health departments prioritized CI/CT efforts on certain people diagnosed with COVID-19 to focus resources and to increase the use of automated outreach. During the August through October 2021 surge, public health departments again prioritized CI/CT efforts on certain people diagnosed with COVID-19 to focus resources, and some public health departments stopped contact tracing altogether. Most public health departments further prioritized certain populations for case investigation during the December 2021 through February 2022 surge and stopped contact tracing at that time (Figure). Concurrently, in January 2022, several influential public health organizations released a joint statement urging a transition away from universal CI/CT to a more targeted approach. This announcement may also have contributed to jurisdictions’ decisions to narrow their focus or stop some or all CI/CT efforts. 17
Timeline of COVID-19 case counts and reported changes in case investigation and contact tracing approaches among 43 state, local, and tribal public health departments in the United States, based on analysis of 43 key informant interviews. Source of COVID-19 case count information: Centers for Disease Control and Prevention. 10
Staffing
Early in the pandemic, public health departments redirected staff working on other public health priority areas, with some staff having prior CI/CT experience but others having little to no experience, and relied on volunteers from the community with public health experience (eg, medical students, public health students) for their CI/CT efforts. With the realization that the pandemic would not be easily contained and that other priority areas needed to resume their essential functions, most public health departments eventually used CDC-provided emergency preparedness funds or dedicated COVID-19 funding to hire contractors. Despite efforts to anticipate pandemic surges and lulls, public health departments struggled to scale staffing quickly and experienced challenges in maintaining an appropriate workforce size. A local public health department in the West noted: We couldn’t just keep people around paying them to do nothing when the cases were low, and yet, when we started seeing growth, it was so quick and exponential that we couldn’t hire and get people trained quick enough. So in every case when we were like “We’re ready to go” . . . the data would start showing that we’ve peaked and were already on the downslope.
CI/CT staff also experienced burnout from the high volume of work, lack of time off, and secondary trauma experienced from interviewing people diagnosed with COVID-19 and their contacts. Despite these challenges, many public health departments cited the incredible dedication of public health staff and the partnerships with other organizations in their communities and contractors as key contributors to successful CI/CT efforts.
Prioritization of Populations
As a result of overwhelming caseloads, many public health departments began prioritizing populations that were at disproportionate risk of severe outcomes associated with COVID-19 for the first time during the November 2020 through February 2021 surge or during the August through October 2021 surge. By the end of the December 2021 through February 2022 surge, nearly all public health departments had implemented prioritization and were no longer calling all people diagnosed with COVID-19. Groups commonly prioritized were adults aged >65 years, people aged <18 years, or children aged <5 years. Public health departments often shifted their prioritization criteria based on vaccination status and local priorities, such as keeping schools open. A local public health department in the South noted, “In this last surge, [people] over 65 [and] not vaccinated were prioritized for outreach, but in a previous surge right before our schools went back to in-person learning, [people] under age 18 were prioritized.”
Public health departments also altered criteria day-by-day based on the volume of cases, with several public health departments noting that they adjusted the age cutoff for older adults who would receive calls (from adults aged ≥50 years to adults aged ≥70 years) based on staff capacity. Key informants noted that prioritization efforts among their public health departments occasionally predated or modified the CDC recommendations. Public health departments followed CDC November 2020 prioritization guidance but often prioritized additional groups, such as people diagnosed with COVID-19 in long-term care facilities or other congregate settings, people included in unusual outbreaks or clusters, and certain age groups based on local priorities.
Implementation of Automated Outreach
Many public health departments developed automated text messages, calls, or emails that they used to contact people with positive COVID-19 test results who were not prioritized for outreach from a live caller. Most public health departments implemented these processes during the November 2020 through February 2021 surge; other public health departments added these options as the pandemic progressed. Information provided in text messages to people with positive COVID-19 test results commonly included links to the public health department website with isolation guidance and a telephone number to use if people with COVID-19 needed resources to isolate. Automated outreach by email or text message often included a survey to collect information similar to that collected in a live case investigation interview. A state public health department in the West noted that implementing an online survey “gave us the ability to focus on people who needed specific help in the moment,” either with wraparound services (eg, food, housing needs) or assistance with medical issues. These automated tools were often integrated into the data management platforms implemented by states, with local public health departments having the option to participate. In addition, a few public health departments implemented automated symptom-monitoring tools, such as Sara Alert, an open-source automated symptom-monitoring tool used after a person has been identified with COVID-19 or has been exposed to COVID-19.
Scaling Back of Contact Tracing
Over time, contact tracing generally followed a similar pattern as case investigation, with many public health departments eventually implementing automated processes to notify contacts rather than making individual telephone calls. During surges, many public health departments focused on case investigation and stopped contact tracing altogether. The timing of this shift varied, ranging from 1 state in the South that focused on case investigation exclusively after the summer 2020 surge and did no further contact tracing, to states that continued some contact tracing during the December 2021 through February 2022 surge. Many public health departments abandoned contact tracing either during the November 2020 through February 2021 surge or during the December 2021 through February 2022 surge as the number of cases overwhelmed staff, although a few public health departments continued contact tracing in environments associated with elevated risk of COVID-19 transmission. Public health departments noted that the success rate of contact tracing declined over time because “people were very stingy with their contacts” and because, by the time they interviewed people with positive COVID-19 test results and asked about contacts, “it was outside of that window to do anything.” As contact tracing efforts declined, public health departments encouraged people with positive COVID-19 test results to notify their own contacts and provided language they could use to notify them.
Innovations for Additional CI/CT Support
Public health departments made other innovations to support CI/CT outreach throughout the pandemic, including developing dedicated community support teams that could facilitate vaccination or connect people with resources to help them isolate and quarantine. People diagnosed with COVID-19 and their contacts could request these services during live interviews or in response to automated outreach. Support from public health departments evolved to offers of additional services; a state public health department in the Northeast noted assistance “with anything from providing food support [and] registering for [Supplemental Nutrition Assistance Program] benefits [to] helping people stay in their rentals and apartments, [providing] domestic violence assistance, [and] getting people into isolation rooms.” Public health departments mentioned food and housing assistance as the most common services that they provided; other services included delivering prescription medication and supplies such as face masks, thermometers, and pulse oximeters and providing linkages to vaccines and therapeutic treatments for COVID-19 when they became available.
Reaching Populations Disproportionately Affected by COVID-19
Public health departments identified Black, Hispanic, and American Indian people; people residing in congregate settings; and immigrants and refugees as populations disproportionately affected by COVID-19 and attempted to reach these groups through CI/CT (Table 2). Because of limited demographic information on laboratory reports, public health departments had delays and difficulties in identifying disproportionately affected populations. Some public health departments used known indicators of disparity, such as living in specific zip codes or the Social Vulnerability Index, 8 to direct their efforts. Strategies to reach these populations included increasing access to testing, establishing community partnerships, recruiting staff from the community, and implementing translation and interpretation services. Many public health departments also had dedicated teams to conduct CI/CT for populations in congregate settings (eg, homeless shelters, correctional facilities) and contracted with hotels to provide isolation and quarantine spaces for people experiencing homelessness.
Illustrative quotes from key informant interviews conducted with state, local, and tribal public health department officials on identifying and reaching populations disproportionately affected by COVID-19 through case investigation and contact tracing, March and April 2022 a
Abbreviations: CDC, Centers for Disease Control and Prevention; CI/CT, case investigation and contact tracing; EDN, electronic disease notification; PHD, public health department.
Forty-three interviews were conducted among local, state, and tribal PHDs.
The CDC EDN system is a centralized electronic reporting system that notifies state and local PHDs and screening clinics of the arrival of refugees and immigrants with health conditions requiring medical follow-up.
Discussion
Our analysis augments publicly available information on states’ approaches to CI/CT by using qualitative data to provide contextual information on factors driving decision-making in state, local, and tribal public health departments. 14 During the COVID-19 pandemic, many state public health departments had to adapt previously existing CI/CT structures (eg, a centralized vs decentralized governance system), often incorporating elements of multiple CI/CT approaches based on different stages of the pandemic and local needs. Public health departments at multiple levels sought innovative solutions to staffing, training, and prioritization of efforts to meet the demands of the swiftly evolving pandemic.
Despite differences in structures and overall capacity, public health departments made similar adaptations to their CI/CT methods over time, including prioritizing populations to focus on highest risk and local priorities, automating outreach to reduce staff burden, focusing on case investigation to identify those most in need, and providing additional support to those isolating or quarantining to reduce the need to leave isolation or quarantine early (eg, to obtain food or medication). The similarity of adaptations might have been spurred by the prioritization guidance released by CDC 11 and/or peer-to-peer sharing of resources and approaches.
Respondents spoke about the difficulty in “right-sizing” the public health workforce, with surges leaving public health departments understaffed as case rates rose and overstaffed as case rates fell. By spring 2022, most public health departments were relying on contractors to meet their surge staffing needs. Overall, state public health departments noted the benefits of approaches used to manage call centers with contractors and flexibly support local, rural, or small public health departments when needed. Although public health departments prioritized populations disproportionately affected by COVID-19 in their CI/CT efforts, the lack of demographic data on laboratory reports made identification of disproportionately affected populations difficult. Implementation of steps to routinely integrate data from laboratory reports with other sources of demographic data could enable public health departments to better prioritize these groups during future outbreaks. The strategies that public health departments used to reach disproportionately affected populations, such as establishing community partnerships and employing staff from the local community, should continue to be emphasized in future efforts to allow equitable implementation of CI/CT efforts. In addition, encouraging people who receive a positive COVD-19 test result to self-notify their own contacts and providing reliable information sites for those contacts would be useful in future outbreaks.
Limitations
Our study had several limitations. First, our findings might not be generalizable to the experiences of all state, local, and tribal public health departments because our sampling frame was based on states that met a minimum threshold of data completeness in COVID-19 data submitted to CDC during the pandemic. Public health departments that did not meet this threshold may differ from those that did. Second, because states selected the participating locality, bias could have been introduced (eg, if localities felt they had to speak positively about their experiences with CI/CT). To balance this risk and allow participants to feel comfortable expressing their perspectives and experiences, we interviewed state and local participants separately, except in 1 state, in which a member of the state public health department participated in the local interview. Third, interviewers asked respondents to reflect on the whole of the response to the COVID-19 pandemic, which could have potential for recall bias. However, to minimize recall bias in questions and to account for frequent changes in staffing and leaders during the COVID-19 pandemic, we encouraged public health departments to include up to 3 total respondents in interviews to supplement gaps in knowledge.
Conclusions
CI/CT efforts are fundamental components of the ongoing public health response to pathogens, including tuberculosis, sexually transmitted infections, and HIV. With the emergence of future pathogens, the responding CI/CT efforts will likely involve many of the same uses and encounter many of the same challenges seen in the response to the COVID-19 pandemic. Public health departments can use lessons from the COVID-19 pandemic to improve CI/CT efforts in future large-scale responses. Prioritizing populations and implementing automated outreach, having flexible additional staffing resources as the number of cases rise and fall, incorporating demographic data into laboratory reporting, providing community connections and support, and asking people to self-notify contacts are useful strategies for public health departments when implementing CI/CT efforts in the future. Similarly, although having an appropriately trained public health workforce that can support day-to-day public health efforts is important, investments in training of other state and local staff are needed to ensure that additional staff are available to scale up and prevent burnout during future infectious disease events.
Supplemental Material
sj-docx-1-phr-10.1177_00333549241239556 – Supplemental material for Experience of Public Health Departments in Implementation of COVID-19 Case Investigation and Contact Tracing Programs
Supplemental material, sj-docx-1-phr-10.1177_00333549241239556 for Experience of Public Health Departments in Implementation of COVID-19 Case Investigation and Contact Tracing Programs by Colleen Staatz, Penny S. Loosier, Ruth Hsu, Michelle Fiscus, Reena Gupta, E. Rain Sabin, Divya Vohra, Holly Matulewicz, Melanie M. Taylor, Elise C. Caruso, Nickolas DeLuca, Patrick K. Moonan, John E. Oeltmann and Phoebe Thorpe in Public Health Reports
Footnotes
Acknowledgements
The authors thank the 43 participating public health departments for sharing insights and experiences. The authors acknowledge the contributions of Xindi C. Hu, ScD, from Mathematica, who provided substantial assistance with organizing and analyzing the information used to select participating sites, and the other members of the research team, including Brigitte Manteuffel, PhD, and Candace Miller, ScD, from Mathematica, and Elinor Higgins, MPH, and Sandra Wilkniss, PhD, from the National Academy for State Health Policy.
Disclaimer
The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The reported research was funded by the Centers for Disease Control and Prevention, under contract no. 75D30121C11647.
Supplemental Material
Supplemental material for this article is available online. The authors have provided this supplemental material to give readers additional information about their work. The material has not been edited or formatted by Public Health Reports’s scientific editors and, thus, may not conform to the guidelines of the AMA Manual of Style, 11th Edition.
References
Supplementary Material
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