contact tracing

While forms of the practice are older, the term contact tracing is first recorded in the 1930s. During World War II, contact tracing was used to track the spread of sexually transmitted diseases. Contact tracing was also notably used to help control and prevent the spread of such communicable diseases in the 20th and 21st centuries, including smallpox, AIDS, SARS, and Ebola, and COVID-19.

So, what, exactly, is contact tracing, and how does it help fight the spread of communicable diseases? It involves three primary stages:

1. When someone is confirmed or suspected to have a communicable disease, they are thoroughly questioned by trained individuals to find out who they might have interacted with—and thus may have spread the disease to—after becoming infected.
2. These people, known as contacts, are identified and made aware of their exposure (e.g., via phone or email) to get any healthy and safety information they might need. This could include symptoms of the disease and what they should do if they think they might have it.
3. The contacts get regular follow-ups so they can be monitored and tested if they show symptoms of the disease.

The goal of contact tracing is mitigation and prevention—to slow or stop the spread of communicable diseases. For some infectious diseases, a person exposed to someone who is infected has to quarantine; if they themselves become infected, they are isolated. Learn more about the difference between quarantine vs. isolation.

While a labor-intensive process, contact tracing has proven highly effective at identifying people who have been exposed and infected, allowing public health officials to monitor their condition and treat them before they can spread the disease to anyone else.

Contact tracing has been at the forefront of medical strategy (and news headlines) during the outbreak of the COVID-19 virus as a way to help prevent the spread of this highly contagious disease. Many governments and organizations around the world have been using contact tracing to try and slow the spread of the novel coronavirus, and ensuring a certain number of contact trainers in the population has been a part of requirements for lifting shelter-in-place restrictions. Medical organizations, such as the Centers for Disease Control and Prevention (CDC) and Johns Hopkins Bloomberg School of Health, have provided free resources for people hoping to train themselves in contact tracing.

Contact tracing does have its challenges, as highlighted during the outbreak of COVID-19. For one thing, contact tracing takes time, and if a disease is especially contagious (as COVID-19 is), it can spread far and fast, making it hard for contact tracing to keep up—underscoring why early and thorough contact tracing is important. For another thing, if an infected person doesn’t show any symptoms (as was the case with some infected with COVID-19), challenging the effectiveness of contact tracing—making diagnostic testing for the disease all the more vital.

To conduct contact tracing, health workers need a lot of personal information, which have led to some objections to the practice as an invasion of privacy (especially when it comes to the use of tracking the movement of contacts using GPS technology on their mobile phones).