COVID-19: Overview of Community Contact Tracing

By Willie S. Morrissey Last updated Jun 11, 2022

We are facing a pandemic that brings with it new challenges and new opportunities in how we respond. One of these new opportunities – community contact tracing – offers a technological update on traditional methods.

First of all, what is contact tracing? It starts with understanding that a person’s risk of contracting a virus is directly related to their exposure to others who are already infected. Contact tracing is a powerful public health tool that professionals use to break chains of disease transmission, protecting individuals and populations from the spread of disease. Contact tracing involves a comprehensive process that starts with interviewing people who are infected with a contagious or communicable disease, i.e. someone who is a confirmed case.

The confirmed case is interviewed by someone trained to ask an empathetic series of questions about other people they have come into contact with over a specified period of time. These contacts are then interviewed to assess symptoms, gather additional information about their exposure, offer resources for testing, and help support the contact’s quarantine, ensuring safe, durable, and effective isolation to prevent further transmission.

Conventional contact tracing has been a manual process. The Centers for Disease Control and Prevention (CDC) has released a standard form and methodology, specifically for the COVID-19 response. Unfortunately, the established process generally does not include the systematic entry of useful location information. To improve the contact tracing process, Esri is introducing the concept of community contact tracing.

The standard CDC form for contact tracing does not capture location data in a usable way. A small change to the exposure information section could provide useful analysis. (Click on the image to see a larger size.)

The Need for Community Contact Tracing

At the very beginning of an outbreak, when we observe human-to-human transmission of infection, contact tracing becomes a robust intervention for containment. However, as an outbreak evolves into a pandemic, transmission progresses to community spread – a situation where infected people do not know how or where they contracted the virus. This is where a location-focused approach can help.

The coronavirus disease 2019 (COVID-19) pandemic is certainly in the community spread phase. And yet, public health authorities around the world are calling for contact tracing to be taken to an unprecedented level, supporting continued efforts to prevent further spread of the virus. If this effort is to succeed, we will all have to think differently.

At Esri, we believe the person-to-person approach inherent in traditional contact tracing should be extended to include person-to-person-to-place, simple innovation with big returns. Including place makes sense in our highly complex, highly mobile and interconnected world. All that is required is enabling the location of contact addresses and community locations during the data collection process.

Benefits of community contact tracing

By adding location information to contact tracing, public health analysts will be able to perform location analytics to illuminate where viral spread is occurring outside of direct, prolonged contact between two people.

Using ArcGIS Pro, connections between people and places can be discovered using a combination of link analysis and centrality analysis which determines the importance of a node at the within the network. In this fictitious dataset, Home Plus connects several cases that were unknown to each other and had no other transmission contacts in their network. (Click on the image to see a larger size.)

Tools such as link analysis and centrality can identify places that may connect otherwise unknown cases and contacts to each other. For example, the person who is a Confirmed Case is shopping at the same home improvement store as a Contact. When places of transmission are identified, decision-makers can take action, whether it’s targeted cleaning and disinfection or strengthening social distancing measures in and around that place. .

The 7-minute video below features an illustrative example demonstrating spatial linkage analysis and centrality measures that capture the importance of person-to-person-to-place relationships.

In the face of the challenges posed by COVID-19, space technologies allow us to think differently. Public health professionals are considering innovative ways to scale up contact tracing efforts, and many recognize that community contact tracing reveals important information to advance interventions.

Public health departments can use GIS to enable location and perform location analysis. Enabling location includes managing data in a system of record and digitizing and streamlining data collection. Location analysis involves examining collected data to quickly identify potential contacts and determine the origin of specific cases. With a location-focused complement to traditional contact tracing, community contact tracing offers increased chances of containing COVID-19 or any other community-spread contagion.

A more detailed video demo is available here. See the COVID-19 GIS hub for location intelligence resources. The Coronavirus Response solutions page provides a collection of maps and apps that can be used by agencies to understand the impact of the virus and share information about the pandemic with the public.

A location-based perspective

The core of contact tracing centers around case and contact interviews. Several support processes require a location lens. For example, many jurisdictions do not have enough contact tracers to meet the need. To be more effective, they could use geography to strategically lead contact tracing efforts in the highest-risk locations.

When a contact is made aware of their exposure to a case, the first recommendation will be to get tested. Resource locators, like the one built by URISA’s GIS Corps, help direct people to their nearest testing facility. As contacts self-quarantine, some may need help finding safe shelter, food options, and health resources. Public health professionals may need to establish new resources in their locality. Geographic analysis can help by making connections between population needs, available resources, and local accessibility in a process called location-allocation.

Map-based dashboards, such as Johns Hopkins University’s famous dashboard, bring real-time and near-real-time insights to executives’ fingertips. Using key indicator data for contact tracing, leaders can see how many case interviews are completed within 24 hours of a positive test report, how many contacts have been tested and how many are positive, and how many of positive contacts can be directly linked to a case or a place.

About the Author

Este Geraghty, MD, MS, MPH, GISP

Dr. Geraghty is Chief Medical Officer and Director of Health Solutions at Esri, where she leads business development for the health and human services industry. Formerly deputy director of the California Department of Public Health’s Center for Health Statistics and Informatics, Dr. Geraghty directed the vital statistics and public health informatics programs. There, she engaged in statewide initiatives for meaningful use, health information exchange, open data, and interoperability. While an associate professor of clinical internal medicine at the University of California, Davis, she conducted research on geographic approaches to influencing health policy and advancing community development programs. A specific area of research concerned the safety of pesticides. In addition to her degrees in medicine, medical informatics and public health, Dr. Geraghty is also a Certified Public Health Professional (CPH) and Geographic Information Systems Professional (GISP).