What Is Contact Tracing?

Health authorities have been using contact tracing for decades to help curb the spread of infectious diseases. Companies dedicated to the practice and public health workers travel worldwide, including to Haiti, Peru, and Rwanda, to identify and track many infectious diseases, from tuberculosis and HIV to sexually transmitted diseases.

In 2014 and 2015, contact tracing was invaluable in stemming the spread of Ebola in West Africa. Experts knew that the spread of the virus could begin as soon as an infected person showed symptoms. Practitioners closely monitored those who were in contact with confirmed cases for 21 days to ensure they received treatment if necessary and to track any other contact. The method also helps quickly identify any other illnesses that could be related to the virus.

The primary goal of contact tracing is to track the spread of a virus to ultimately limit the exposure and, in the case of an epidemic or pandemic, shorten the period during which an entire population must be in an emergency situation and take extreme measures.

The World Health Organization divides contact tracing into three steps:

Step one is identifying the contacts. Authorities will ask the infected person to consider everyone with which they have come into contact since the presumed onset of their illness. This can include family members, coworkers, friends, and anyone else with whom they spent a specified period of time in close proximity, such as a doctor or other service provider.

Step two in contact tracing is to list the contacts. Every contact the infected person listed should be recorded and alerted to their status. Medical authorities will let the contacts know what this status means and how they should proceed — if they should monitor for symptoms, practice isolation, quarantine themselves, or seek medical attention.

Finally, health authorities should follow up with contacts. All contacts on the list should receive regular follow-ups to monitor them for any signs or symptoms of infection. In some regions, this may include reaching out to all contacts at the end of any required quarantine period to confirm that they have completed the requirement and to check a final time that they are symptom-free.

The first thing health divisions must do upon deciding to undertake contact tracing is determine the parameters for the specific infection. This is important information they must pass on to both infected individuals and all contacts.

These details are disseminated to all the contacts and include the requirements for quarantine and other practices expected of them. Because expectations can vary significantly from region to region, health practitioners may also need to reach out to neighboring regions to discuss enforcement for any contacts living further afield. Though contact tracing usually involves requesting that contacts self-monitor for symptoms, in some cases, health authorities may actively monitor affiliated individuals.

Technology seeks to improve processes in every field these days, and the tracking and treatment of infectious disease is no exception. The goal of this software is to lessen the workload of data collectors by enabling self-reporting and using location data to more accurately identify contacts. The CDC currently outlines two types of digital tools: those that allow for reporting and tracking cases, and proximity tracking apps that use GPS to identify contacts.

Research is ongoing to determine the best ways to collect data for future epidemics. Not surprisingly, the biggest challenge is acquiring all the necessary, and accurate, information as quickly as possible, in order to act promptly and address outbreaks before they are out of control.

Another study investigated how helpful contact tracing truly is by reviewing efficacy and budget allocations. Primarily, they found that the more resources an agency expends to track those further removed from the infected individual, the less notable the effects of the tracing. This makes sense because contacts more removed from the host — for instance, the doctor of the roommate of the infected person’s girlfriend — are less likely to be infected.