Establishing the foundation: enhanced case investigation, case finding, and containment efforts during shelter-in-place

On February 25, 2020, San Francisco’s Mayor, London Breed, was the first city mayor in the United States to declare a state of emergency to mobilize financial resources to focus on COVID-19 preparedness [2]. On March 17, 2020, Mayor Breed responded to recognition of widespread community transmission and increasing public awareness of the need to ‘flatten the curve.’ In coordination with five other Bay Area counties and the City of Berkeley, she ordered San Francisco residents to shelter in place. By then SFDPH had determined that 58 people had fallen ill with COVID-19 and one had died in a city of 900,000 inhabitants [4], and the San Francisco Public Health Laboratory was performing approximately 260 RT-PCR tests per day [5]. The SFDPH Disease Prevention and Control Branch had already mobilized to respond to the epidemic, performing 150-200 case investigations a week by the time of the health order. Nonetheless, SFDPH recognized that swift action was imperative to prevent overwhelming transmission that would render more enhanced case investigation and contact tracing unfeasible [6]. The SFDPH Department Operations Center (DOC) leadership identified the need to enhance capability to implement a robust and expansive contact tracing. Moreover, DOC leadership recognized that to have maximal impact, contact tracing expansion needed to happen in parallel with other critical elements, including (1) increased testing, particularly for populations at highest risk for COVID-19 morbidity and mortality, (2) mobilizing a workforce to expand capability and implement case investigation and contact tracing, and (3) ensure holistic, social services to enable provision of adequate isolation and quarantine spaces for all those in need, ensuring equitable distribution to all.

Increasing access to testing

The DOC Testing Branch scaled resources to increase case finding for all contacts of COVID cases. It responded to the need for mass testing to identify outbreaks in congregate settings, with particular focus on long-term care facilities, homeless shelters, and single-room occupancy hotels (SRO) [7]. By the end of April 2020, increased diagnostic capacity, in tandem with increased capability to collect more samples at more testing venues, meant that the city was able to broaden its testing criteria to include all close contacts of confirmed COVID-19 cases, without regard to symptoms (or absence of them) among contacts. As well as overseeing implementation of these key elements to meet the needs of the city’s entire population, SFDPH instituted plans to implement an ambitious plan to mobilize a workforce of contact tracers sufficient to address the anticipated increase in cases. SFDPH was able to achieve this with assistance from the University of California, San Francisco (UCSF) which supported training, analytics, and informatics with expertise and project management capability. Only in this way would San Franciso’s health authority be able to recommend loosening of shelter-in-place requirements.

Mobilizing an expanding workforce

Recognizing that there was a pressing need to rapidly expand the workforce dedicated to contact tracing, SFDPH looked to other countries and epidemiologic modeling to estimate the number of individuals who would be needed to undertake contact tracing. Wuhan China mobilized 9000 personnel for a population of 11 million [8]; Canada activated 2700 persons to support its contact tracing effort [9]. The SFDPH contact tracing planning team estimated a need for 100–150 contact tracers for a population of approximately 900,000. To validate this estimate, our Case Investigation and Contact Tracing (CICT) management team, composed of public health experts from SFDPH and UCSF, projected potential needs based on various scenarios for how the number of incident cases and their contacts might increase over time. We also approximated the time it might take to perform contact tracing, even using efficient technological tools. Later, the CICT management team revised these initial projections by assessing how many cases and contacts the team reached in a given shift.

Given that SFDPH had already activated several members of its staff to work on COVID-related activities, the CICT management team discussed where else to find personnel for meeting this pressing human resource need. In partnership with the University of California San Francisco, SFPDH proposed a plan to rapidly train a workforce of medical students and retired clinicians, city and county (CCSF) librarians, and other civil servants who were unable to fulfill their normal duties under the shelter-in-place order. Training specific to their new responsibilities included ‘motivational interviewing’ (a directive, client-centered counseling style for eliciting behavior change) [10] and the confidentiality and privacy requirements of the CICT program, as outlined in the United States Health Insurance Portability and Accountability Act (HIPAA). The CICT training team, led by staff and faculty from UCSF, conducted most of the training on Zoom®; topics included disease transmission (basic information), principals of case isolation and quarantine for contacts, ethics of public health data collection, importance of cultural sensitivity, specifics of local processes and data collection, and characteristics of the San Francisco healthcare system.Footnote 1 The training required completion by all participants of sections on confidentiality, privacy, and HIPAA compliance.

Ensuring comprehensive support

The CICT management team repeatedly revised the contact tracing workflow to optimize client-centered care, team efficiencies, and data collection. (See Fig. 1.) SFDPH recognized a need for substantial support for many of those infected with COVID-19 (cases) and their contacts to safely isolate and quarantine. Thus, the DOC Containment Branch expanded capacity to isolate and quarantine all such people outside of their residences. The Containment Branch also made agreements with hotel owners and with a newly developed Internet-based bed management system (RTZ Systems, Lafayette California) in partnership with multiple CCSF departments, businesses, and community-based organizations. Through a coordinated program across several departments of city government, the DOC Containment Branch also arranged for food deliveries, financial resources, and cleaning supplies for all those eligible.

Fig. 1

Current contact tracing workflow