How Tarrant County uses contact tracing to track local spread of coronavirus
The Rev. Robert Pace stood in front of 45 people on March 4 and led the Lenten program at Trinity Episcopal Church in Fort Worth.
He felt sick days earlier and was diagnosed with the flu. He still had a deep cough, but his fever broke. He felt safe enough to go to the church, but stood away from his worshipers. Little did Pace know, he was actually infected with the novel coronavirus.
When he was finally diagnosed with COVIRD-19 six days later, epidemiologists at the Tarrant County Public Health Department had the daunting task of tracking down every single person Pace had been in contact with while he was showing symptoms.
The process — called contact tracing — is how countries like South Korea have been able to stop the spread of coronavirus without shutting down the economy. Tarrant County has used contact tracing to track people who have likely been exposed to COVID-19 and force them into isolation. But a lack of resources, legal barriers and an increase in coronavirus cases could make widespread contact tracing difficult.
“At some point it’s going to get so widespread that that may not happen,” said Tarrant County judge B. Glen Whitley.
Contact tracing is lingo for the process of reaching out to all the people who have been in contact with somebody who has tested positive for coronavirus. Those who have had contact with the person are usually told to self-quarantine for at least 14 days and pay close attention to any symptoms they develop.
Diana Cervantes, a professor of epidemiology and biostatistics at UNT Health Science Center, said contact tracing should involve reaching out to everyone who may have come in contact with the infected person on an average day.
A high volume of testing and contact tracing can allow areas to fight the spread of a virus without resorting to shutting down the general population. But there’s a contradiction: The more people testing positive means the more people that resource-limited public health labs like Tarrant County’s must contact trace.
When Pace tested positive, he was the only case in the county for three days. Tarrant County is now dealing with more than a dozen new cases of coronavirus every day, each of which requires contact tracing.
“I can’t imagine them being able to do this for hundreds of people,” Cervantes said.
The Tarrant County Public Health department did not respond to multiple requests for specific questions about its contact tracing and how much tracing it can do given the greater frequency of coronavirus cases. A spokesman for the department provided a statement saying: “Tarrant County Public Health does contact tracing. The process involves contacting the case, asking them where they have been during the last 14 days and whom they might have been close to. We then call their contacts based on their exposure risk and ask if they have symptoms. If they meet the CDC criteria for symptoms, they may then be referred for COVID-19 testing.”
Denton County Public Health said it was still doing contact tracing (the county had 83 confirmed cases as of Thursday) and had moved extra staff to assist four epidemiologists who handle the bulk of the duties.
At Southern Methodist University, three students tested positive for coronavirus after returning from spring break. Two of them tested positive outside of Texas. University president R. Gerald Turner said in a message to the SMU community that “the University is making every effort to inform individuals most likely to have been in close proximity to these students, such as classmates, faculty members and members of the graduate student’s international study team. Those persons more likely to have been in contact with them are being advised to self-monitor for symptoms of fever, cough and shortness of breath.”
When he tested positive in Tarrant County, Pace said the public health department asked him “in great detail” for information about everybody he came into contact with.
“They were so thorough in what they did and they followed through with everybody,” he said. “Anybody I came in contact with did quarantine.”
That included the 45 people at the Lenten program and two doctors. Every day, the health department followed up with those in quarantine to ask if they had a fever, Pace said.
Whitley said people identified as being in contact with someone who tested positive for COVID-19 would be issued a control order that forced them to quarantine. Tarrant County has reserved apartment buildings for people who are ordered to quarantine and have a living situation that makes it difficult. Whitley said likely hundreds of people have been forced to quarantine because they’ve been found to have contact with somebody who tested positive for COVID-19.
In South Korea, the government has legal powers during public health emergencies to seize, without a warrant, a person’s cellular GPS data and credit card data to determine the recent locations of a person who has tested positive for coronavirus and contact trace up to hundreds of thousands of people. Those powers, along with a proportionally higher amount of testing than in the United States, have allowed South Korea to slow the spread of coronavirus without shutting down its economy.
The shortcomings of contact tracing in Tarrant County, particularly as coronavirus cases increase, are one reason why the county enacted its stay at home order, Whitley said. He said that if people follow the order they will be spending time in close proximity only to their households, and all of their contacts will be known.