WRAL Investigates

Tracking those infected people have contacted is key to slowing coronavirus

Posted May 8, 2020 4:36 p.m. EDT
Updated May 8, 2020 8:18 p.m. EDT

— A key tool in containing the spread of coronavirus, according to state officials, is increased contact tracing, or tracking down and following up on anyone who had close contact with a person infected with the virus.

With more than five months of contact tracing going on around the world since the first case of COVID-19, the illness associated with the virus, was identified, a clearer picture of what researchers have found is starting to emerge.

Dr. Muge Cevik, an infectious disease researcher at the University of St. Andrews in the United Kingdom, took to Twitter to explain more than a dozen contact tracing studies that have been completed during the pandemic. The cases covered investigations in the United States, Asia and Europe.

One study traced 10 cases in the U.S. with 445 close contacts, and it found only two new positives, both in the same household.

Another U.S. investigation traced 372 close contacts from a sick husband and wife. While 43 showed symptoms, none tested positive.

The researcher’s conclusions: household contacts showed the highest risk of spread, with chances up to 20 percent. Family gatherings for things like funerals, birthday parties and reunions also had a high risk with a common factor – shared food.

Cevik also concluded short, casual interaction didn’t appear as contagious, though social distancing remains important as a precaution.

"I’m most struck by the fact that we still have so much uncertainty about what’s going on," said Alun Lloyd, a mathematical biologist at North Carolina State University who specializes in infectious disease spread.

Lloyd said one fascinating aspect of the pandemic is all of the real-time research.

"The more information we have, the better," he said, adding that he believes most studies miss asymptomatic and surface spread.

"That could be up to half of all the cases," he noted.

There’s no evidence asymptomatic people are more contagious than those who have minor symptoms but are unaware they’re carrying the virus.

Lloyd is working on a modeling study that combines cellphone BlueTooth data with testing to help trace contacts. While recognizing privacy and participation concerns, he said the data is important.

"You could then look at their contacts because you’d have all this information that had been stored in this cellphone tracking set up," he said.

North Carolina is working on doubling the number of contact tracers from 250 to 500. So far, Wake County hasn't added to its tracing workforce, although local librarians are being pressed into service to assist while libraries remain closed.

A Wake County spokeswoman said officials are waiting for restrictions on movement and gatherings to relax even more, possibly in the second part of the state's three-phase plan to resume business and social activities during the pandemic. That will give tracers more opportunity to track someone’s movements in different environments to see how many people become infected, the spokeswoman said.

Every study adds a piece to the puzzle of sorting out the coronavirus.

So far, several contact tracing studies raise questions about whether the virus easily spreads in public settings. The same studies also make it clear the virus can quickly spread when there’s elongated close contact in home or congregate living settings like nursing homes or prisons.

No matter the situation, Lloyd said now is not the time for people to let their guard down.

"I think we should, at this point, still be cautious until we have more information and a clearer picture of what exactly is going on," he said.

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