Coronavirus: What is Contact Tracing?

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Contact tracing is a method of controlling the spread of infectious disease in communities. Some cities and towns in the United States are now using contact tracing to limit further transmission of COVID-19, the disease caused by the SARS-CoV-2 coronavirus.

Jonathan Zenilman, M.D., an expert in infectious diseases, explains how contact tracing works and how people can get involved.

Contact Tracing: How It Works

The U.S. Centers for Disease Control and Prevention defines contact tracing as “part of the process of supporting patients and warning contacts of exposure in order to stop chains of transmission.” For decades, public health workers have used contact tracing to slow down and contain transmission of tuberculosis, sexually transmitted infections and other illnesses.

Contact tracing can:

  • Break the chain of transmission in contagious disease outbreaks.
  • Prevent local surges in the number of sick people that can overwhelm hospitals and resources.
  • Hasten the ability of communities to safely reopen schools, businesses and public areas.

Contact tracers may be assigned to address outbreaks in long-term care centers, group homes, homeless shelters, correctional facilities and areas where crowded, multigenerational households are common.

The concept is simple: When a person tests positive for COVID-19, the contact tracer:

  1. Immediately contacts the infected person and encourages him or her to self-isolate before others can be infected.
  2. Works with that person confidentially to determine with whom there might have been contact during the time he or she was contagious.
  3. Notifies those people and explains the risks and symptoms of COVID-19 so they monitor their health and self-quarantine.

Contact tracers may be assigned to address outbreaks in long-term care centers, group homes, homeless shelters, correctional facilities and areas where crowded, multigenerational households are common.

Contact Tracing and COVID-19

Although COVID-19 is a pandemic, its spread across the United States is not even. Instead, the coronavirus is infecting people in a patchwork of local outbreaks, some involving nursing homes, prisons, meatpacking plants and even large social gatherings. Contact tracing can help detect how COVID-19 is moving from person to person in these events.

“From a contact tracing standpoint,” Zenilman says, “COVID-19 is similar in some ways to tuberculosis because of how it is transmitted. The contact tracer needs to work with an infected person to recall anyone they have been close to and help people figure out which are the more high-risk contacts.”

It’s not easy. “People know who they live with, but may not know the names of everyone in their class or congregation,” he explains. “For instance, the infected person might have had a conversation with a cashier at the supermarket. If the person didn’t know that cashier by name, the contact tracer would ask what the cashier looked like and try to find him or her.”

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Contact Tracing Training

A demand for large numbers of skilled contact tracers is growing. One estimate says that in any particular area, a successful program will need at least 15 contact tracers for every 100,000 people, and double that number for places hard hit by the pandemic.

Free contact tracer training, provided by the Johns Hopkins Bloomberg School of Public Health, is available online. The five-hour course covers:

  • Facts about infection with the SARS-CoV-2 coronavirus, which is causing the global pandemic, and COVID-19.
  • Identifying an infectious contact.
  • Creating a timeline for public health intervention.
  • Case investigation, including how to overcome potential barriers.
  • Ethical considerations relating to contact tracing, isolation and quarantine.

Contact Tracing: A Special Talent

In addition to proper training, a good contact tracer needs to have a way with people. “This is a very interpersonal activity,” Zenilman says. “In general, contact tracing works when it’s conducted by people with extraordinary interpersonal skills and a desire to help others.

“As a contact tracer, you’re asking people who they’ve been hanging out with, and that can involve getting someone to disclose personal information. You also have to help people remember details of otherwise unremarkable days. Good interview skills can help motivate them to reveal information.”

Then, after the interview, there’s the investigation. “You have to be able to find those contacts, and get creative about rooting out details, which can involve being nicely persistent,” he says.

Contact Tracing: Past and Present

“Contact tracing is a fundamental, nuts-and-bolts public health tool that has been used for 80 years. At its core is interpersonal interaction,” Zenilman says.

“There are some new technological advancements and tools, and although an app can help, ultimately, nothing can replace the human element. This is core public health practice, and although it has been ignored for a long time, the COVID-19 pandemic is creating a new awareness of its value.”

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Coronavirus (COVID-19)

What you need to know from Johns Hopkins Medicine.

Posted July 24, 2020.