What is contact tracing? How experts are tracking coronavirus infections

President Trump's COVID-19 diagnosis highlights the importance of contact tracing. What does it entail?
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/ Source: TODAY

After a Rose Garden event announcing the nomination of Judge Amy Coney Barrett appears to have led to several positive coronavirus cases among high-ranking politicians, including President Donald J. Trump, there have been renewed questions about contact tracing, the method that health departments use to identify coronavirus exposures.

With more officials continuing to test positive and others still quarantining after possible exposure, contact tracing is more important than ever, especially when noting the movements of the president and his team in the period between the Rose Garden event and his announcement of a positive test early Friday morning. In that time, the president traveled to several states and interacted with hundreds of supporters.

What is contact tracing?

According to Linda Niccolai, Ph.D., a professor of epidemiology at the Yale School of Public Health, contact tracing is the "process of identifying and notifying people who have been exposed to a person diagnosed with COVID."

"The goal is for them to know about this exposure so they can monitor themselves for symptoms and self-quarantine," said Niccolai. "The goal of the quarantine is so that if they are infected, they will not expose other people. In this way, contact tracing can be very helpful to prevent ongoing transmission in the community."

Dr. Crystal Watson, a senior scholar at the Center for Health Security at Johns Hopkins University, said that anyone contacted by a contact tracer, or anyone who has had substantial contact with someone who has tested positive for COVID-19, should isolate for at least 14 days and monitor themselves for symptoms. Significant contact is defined as being within six feet of someone for more than 15 minutes.

Under those recommendations, many people at the Rose Garden event where Barrett was nominated to the Supreme Court should be self-quarantining right now, including Vice President Mike Pence, since the virus take up to 14 days to incubate.

"The purpose of contact tracing is really to break chains of transmissions, because if those individuals are indeed infected, then they would be at home, rather than out in the community and spreading it to others," Watson said.

How is contact tracing done?

In most cases, contact tracing is conducted by a public health department at either the state or local level. Watson said that sometimes those departments may partner with other organizations to help with staffing and reaching out to contacts, but health departments generally spearhead the effort.

"When a person is diagnosed with COVID, they will be interviewed to learn about their recent close contacts," explained Niccolai. "The look-back period for close contacts is usually 2 days prior to symptom onset in the index case or 2 days prior to the COVID test (if asymptomatic). The contacts are then notified of the exposure, without revealing the name of the person with COVID. They are encouraged to be tested for COVID and monitor for symptoms."

Watson said that the White House is using an internal team for contact tracing, which is not unheard of, but since the scope of potential exposures is wide, there should be multiple health departments involved, including departments from the states that the presidential team traveled to in recent days. Since officials from many different states gathered at the Rose Garden event, those states should also be preparing for contact tracing.

"In this case, there are a lot of potential exposures not just within the White House but also outside across different jurisdictions and separate states, and so those health departments should be notified and provided all the information that they can get, related to who was at those events and how they can get in touch with them, and I'm not sure that's happening," Watson said, adding that it seems that the White House is not "effectively" using public health resources at the moment.

"It sounds like it's the White House medical team that's running contact tracing in the White House and I hope that they have epidemiologists and public health experts in that process but they also have the CDC (Centers for Disease Control and Prevention) at their disposal," said Watson. "So I hope that they will reach out to other experts because this is a labor intensive and complicated process to do case investigation and contact tracing and so I think they probably could use more public health expertise in that."

There have been reports that the White House has not properly informed others, including Democratic nominee Joe Biden's campaign and New Jersey health officials trying to contact trace attendees of Trump's Bedminster fundraiser, about the positive tests of the president and several other staffers and officials.

"It is going to be complicating if they're not reaching out, especially if there are more individuals who are sick at the White House that haven't been publicly reported," said Watson. "That's going to cause transmission to go unrecognized."

Niccolai said that in general, it can be difficult to contact trace large gatherings like the Rose Garden event.

"First, there are many people who need to be notified. That can take a lot of time and resources," Niccolai said. "Second, it may be difficult to know everybody who was at a large event or gathering. ... Third, not everybody at a large gathering may meet the definition of a close contact and that may be difficult to determine. Finally, geographic dispersal after the event also poses a challenge. The authority to perform contact tracing lies with local health departments, so it may be necessary to identify and work with a large number of local jurisdictions."

What does contact tracing look like?

Exactly how a contact tracer reaches out to someone can vary based on local regulations and protocols.

"Many times it will be a phone call," said Watson. "Sometimes it may be a text message. It really depends on what information they've been provided from a health care provider or a laboratory where the positive test was so they may reach out in different ways."

Niccolai said that phone calls tend to be preferred since they present "an opportunity to provide more detailed information" along with "additional support and referrals." Some programs may check in throughout a person's 14-day quarantine with additional calls or texts to provide support.

Watson said that some difficulty with phone calls is that people may not answer a call from a number they don't recognize.

"It's a tough job," she said. "It's hard to get ahold of people, and it's hard to convince them to stay on the phone. I just encourage everyone to cooperate as much as they can."