Contact tracers struggling with surge
Sharp rise in local COVID-19 cases overwhelming efforts to find those exposed to infected residents
The surge in COVID-19 cases since mid-May has strained the ability of Houston and Harris County’s health departments to investigate infected residents and find each person they could have exposed to the virus, public health officials leading the effort said.
Delays of up to several weeks in receiving lab results, which sometimes contain sparse or inaccurate contact information, mean contact tracers often miss a critical window to warn potentially pre-symptomatic COVID-19 carriers to isolate away from family, friends and co-workers — a crucial step to limit the spread of the virus.
The county’s average daily new caseload of about 1,550 is more than twice the number investigators can process, a failure that leaves the Houston area, once lauded by the White House as a model for how to manage COVID-19, struggling to regain control of the pandemic.
“The volume of new cases is more than we can keep up with at this point,” said Dr. David Persse, Houston’s health authority. “If people
don’t isolate and don’t quarantine, that’s where the rubber meets the road. That’s what slows down the virus.”
Contact tracing, one of public health’s essential tools, is a tried-and-true method since the 19th century of containing outbreaks of disease including typhoid, tuberculosis, measles and Ebola, University of Houston medical historian Helen Valier said. Researchers credit the method with helping South Korea contain its coronavirus outbreak in the early spring.
The tactic, however, typically is employed in small outbreaks, not uncontrollable transmission levels such as those seen in Harris County since late May that make such detective work close to impossible.
“You don’t want a situation where it’s a raging fire all the time, where there are cinders falling and igniting different infection points,” Valier said. “You need to have some sort of control to have effective contact tracing, to have cases falling or at least plateaued.”
The tool has never before been used on an outbreak of this scale, said Crystal Watson, a Johns Hopkins Public Health scholar.
The National Association of County and City Health Officials recommends 30 tracers per 100,000 people to handle the COVID-19 pandemic. Using that formula, Harris County could need 1,410. Combined, the city and county have fewer than 600.
Likewise, the state’s contact tracing effort, meant to help local health departments, had met just 70 percent of its staffing goal at the end of June.
“I don’t want to say it’s not feasible, but I just think it’s incredibly daunting to conduct tracing with this level of virus transmission going on in Houston, Harris County and the state of Texas,” said Peter Hotez, an infectious disease specialist at the Baylor College of Medicine. “For contact tracing to be successful, you need to first bring down virus transmission to low levels, then have a contact tracing infrastructure in place.”
Persse said investigators were able to successfully contain the first COVID-19 outbreak detected in Houston, which was traced to vacationers who returned from a Nile River cruise in late February. But that investigation was a puzzle for which contact tracers had all the pieces: The handful of cases could each be tracked to someone who had been infected in Egypt.
With more than 36,000 active cases in Harris County as of Sunday, that kind of success no longer is possible, he said.
“We are in an uncontrolled spread,” Persse said. “We’re not going to be able to stop it. But whatever we can do to slow it down is worth it.”
Public health officials and researchers agreed that despite its limited effectiveness now, contact tracing is a worthwhile endeavor that will improve when local cases decline.
Test delays
Two main contact tracing efforts are underway locally. One by the city health department tracks cases reported within Houston; the second by Harris County Public Health concentrates on test results within the unincorporated parts of he county.
Since mid-May, Harris County Public Health has been able to contact 60 to 65 percent of COVID-19 patients, said Dr. Umair Shah, director of Harris County Public Health. The county met its goal of hiring 300 contact tracers at the end of May.
Investigators prioritize the most recent tests first, where there is the greatest chance of convincing a patient to quarantine quickly.
“If we get your lab three weeks after you took your tests, or even a month, that delay means, as an epidemiologist, while it’s important to log a person, honestly, I can’t do much for community transmission at that point,” Shah said.
The process begins when the health department receives test results from public and private labs. Some arrive via fax and must be manually entered into the department’s online system; a 3-foot-high stack of results spit out by the machine illustrates the enormity of the task.
Making matters more difficult, he said, the information that labs share is inconsistent and often incomplete. Missing contact information, dates of birth and addresses force staff to burn valuable time scouring databases and sleuthing on the internet. Sometimes they discover a patient actually lives in Galveston or Fort Bend County and forward the case file to the appropriate jurisdiction.
High caseloads also continue to be a problem. The county can process 250 to 300 a day, Shah said, but is averaging 481.
“So, if I got 500 yesterday, 500 today and 500 tomorrow, now that’s a sixday workload you received in three days,” Shah said. “And the more the cases go up, the more you’re stressed to try to reach them.”
County Judge Lina Hidalgo,
who fretted that the number of cases was too high six weeks ago when they were a fraction of what they are now, said she is sure the county effort “has made a difference to some people” but called it “a minor tool at this point.” She said tracing will not play a central role until case numbers plummet and testing turnaround times improve.
She repeatedly has sought Gov. Greg Abbott’s permission to again issue a stay-at-home order, which successfully flattened the curve of cases in March and April. Abbott told Houston television station KRIV on Thursday that a second shutdown would be the “last step taken.”
Goal not met
The Houston Health Department is at a bigger disadvantage. Persse said his teams are able to process about 300 cases per day; the city is averaging more than 1,000.
The Health Department has hired just 232 contact tracers out of its goal of 300, a spokesman said. They work on the sprawling third floor of the George R. Brown Convention Center, which otherwise is empty as the city has refused to permit large indoor gatherings. In the first week of July, they were able to contact about 62 percent of the positive cases they were given.
Former restaurant worker Christopher Lam said he sought more reliable employment during the pandemic; retiree Robert Paterson said he wanted to help with the response. They call 25 to 30 COVID-19 patients and their contacts a day. Some are scared, they said. Some, especially those who speak English as a second language, said they were grateful for the check-in.
A small percentage are dismissive of self-isolation or spooked the government is calling and asking personal questions. The tracers work to build a rapport.
“Most people are receptive, but they are a little defensive,” Lam said. “They’re always asking, ‘Who are you?’ I tell them I’m with the Houston Health Department and show them we’re here to help.”
A particular challenge is convincing a contact to selfisolate and get tested, Paterson said, since privacy laws prevent the tracers from divulging which patient listed them as potentially exposed.
There are other successes. Three members of Harris County’s tracing team described the work as rewarding, if emotionally taxing. Investigator Preeti Rao described a family with several COVID-positive members who were reluctant to quarantine because they needed to earn money.
“They were on the verge of being evicted within a few days,” Rao said. “They were giving their infant son water, because they didn’t have any food at all at home.”
Rao helped connect the family with community groups who provided groceries, diapers, baby formula and rental assistance so they could avoid exposing others to the virus.
And there are encouraging signs in the data, even if they are few. COVID-19 hospitalizations in the 25-county region have flattened in the past week, as has the number of infected patients needing intensive care. Persse said residents should not view this glimmer of hope as a signal the worst has passed.
“People need to picture that we’re in a truck driving 100 mph down the freeway, and we finally stopped accelerating,” Persse said. “Well, we’re already going 100 miles an hour. That doesn’t mean you take your foot off the brake.”