Texas’ COVID testing has dropped as positivity rate climbs, giving virus ‘upper hand’
As hospitalizations of patients with the novel coronavirus and daily new cases in Texas have begun to fall from record levels, the state’s positivity rate has skyrocketed to an all-time high.
As of Tuesday, Texas’ seven-day average positivity rate was at 24.5%, according to Texas Department of State Health Services data. Public health experts have said that for contact tracing to be effective, the number of positive cases out of those tested should remain below 5%.
And the increase in positivity hasn’t been coupled with a rise in testing. Instead, it has decreased by tens of thousands of tests. The state reported an average of 34,188 new viral tests a day for the week ending on Aug. 8, down from an average of 62,801 for the week ending July 18.
A high positivity rate with a drop in testing indicates that the state is not testing everyone it should — like those who may have been exposed, but are asymptomatic — and is likely significantly undercounting the number of cases, public health experts said.
“The fact that we are hitting over 20% of the tests that we’re taking are coming back positive from the state of Texas just says that we are missing the vast majority of cases that are out there,” said Benjamin Neuman, the head of Texas A&M University-Texarkana’s biology department and a virologist who has worked with coronaviruses for over two decades.
If testing had remained steady and the positivity rate decreased, that would indicate the state is at least testing enough to corner the virus and understand its spread. But the positivity rate rising like it has “shows us that the virus has the upper hand right now,” Neuman said.
Drop in testing
Catherine Troisi, an epidemiologist with UTHealth School of Public Health in Houston, said it’s unclear why there’s been a decline in testing. It could be that some people who should get tested haven’t been reached by contact tracers letting them know they’ve interacted with a positive case. Others may have simply given up on getting tested after facing delays of a week or more in getting results back.
“People are just weary at fighting the the hurdles to get tested,” said Rodney Rohde, an epidemiologist and chair of the clinical laboratory science program in Texas State University’s College of Health Professions.
Some metro areas, like Austin, have reported a decline in the demand for tests, and relaxed their criteria for who is eligible. That’s not the case in Tarrant County.
Tarrant County’s publicly supported drive-thru test sites are still booked out like they were in early July, said Brian Murnahan, a spokesman for Tarrant County Public Health. At the time, residents had reported being unable to secure an appointment despite qualifying, and as many as 1,500 people attempted to schedule an appointment per day.
In the last month, several sites have been added in an effort to increase capacity, Murnahan wrote in an email Wednesday.
It wasn’t until late June that Texas had consistently begun to meet its goal of conducting at least 30,000 tests a day. Throughout July, testing capacity increased, reaching more than 60,000 new tests a day.
During a press conference Tuesday in Victoria, Gov. Greg Abbott credited the massive increase in testing in July, in part, to targeted efforts to test hot spots. Abbott promised a similar surge was on the horizon, with four testing sites in Harris County that will be able to test up to 5,000 per day, and same-day testing in nursing homes.
“Also, I have been working with some labs in the state of Texas to increase our ability to do testing in schools, knowing how important that will be. So going forward, especially in September — but maybe before then — you should anticipate seeing another increase in the number of people being tested,” Abbott said.
As for the positivity rate, Abbott pointed to young adults who may have contracted the virus but aren’t showing symptoms unknowingly spreading it to others coupled with small gatherings of family and friends that can lead “to massive spreading events.”
Flattening in Tarrant County
Tarrant County’s positivity rate has been on the decline.
After exceeding 20% throughout June, the rate was at 13% as of Saturday, according to county data.
“In that sense, it’s not terrible. Of course, we can and should do better,” said Rajesh Nandy, an associate professor of biostatistics and epidemiology in the University of North Texas Health Science Center’s School of Public Health.
However, that figure may not represent the complete picture.
While testing data does include tests conducted by private labs, the county’s dashboard notes it does not reflect all tests being performed in Tarrant County. A spokesman for Tarrant County Public Health did not immediately clarify what percentage of private labs are reporting test data.
Confirmed cases in Tarrant County have trended downward from the over 4,000 cases reported the week of July 5. When taking into account both hospitalizations and emergency room visits of suspected COVID-19 patients, Nandy said it’s more realistic to say that the numbers have flattened from the records set in July.
“In the North Texas counties, although the number of reported cases declined. ... I can say with more confidence that the reality is that the numbers have plateaued,” said Nandy, who has been closely tracking Tarrant County’s data on hospitalizations, cases and mobility over the course of the pandemic.
“Still, we have a reasonably high number of new cases,” he said.
COVID-19 Hospitalizations over Time
Coronavirus daily hospitalization counts in Texas and the larger Trauma Service Areas, beginning April 8, 2020. Data provided by Texas Health and Human Services.
Similarly, hospitalizations of COVID-19 patients and new cases have fallen from the highs of over 10,000 reported in July. Abbott said Tuesday that while “the numbers are moving in the right direction ... it is fair to say that hospital capacity by those who are positive for COVID-19 still remains too high.”
On Monday, Texas’ new confirmed cases represented nearly 11% of the new cases reported in the U.S. that day — a share that Neuman said he’s worried Texans are adopting as an acceptable level to return to normal life.
“Complacency with an extremely high — by U.S. standards or world standards — amount of coronavirus cases is a very dangerous thing,” Neuman said.
Returning to the classroom
And experts worry that school openings will only exacerbate the situation.
During a press conference Tuesday in Beaumont, Abbott stressed that the Texas Education Agency has provided strategies, like students wearing masks and staggered start times, which will help schools avoid scenarios of crowded hallways seen in pictures from Georgia.
But Troisi said it’s inevitable cases of COVID-19 will spread in schools, especially with Texas’ high level of spread.
“The virus is still out there. It’s very infectious. And we don’t have any way of stopping the spread,” Troisi said. “We don’t have a vaccine. We don’t have any prophylactic medications. So the only way we have of stopping spread are the public health measures of physical distancing — which you can do in a school, but it’s really hard.”
Without a strong national or statewide strategy around school openings, people are simply doing the best they can, Rohde said.
“And that can be problematic, because you might need to think about strategically rationing tests in areas that are super low prevalence and maybe shipping more towards Dallas, or Fort Worth, or Austin, or wherever, that have bigger school districts,” Rohde said. “I still worry that we’re behind on the strategic policies for everybody to follow.”
Ultimately, Rohde stressed that people will have to be ready to be flexible in case of outbreaks and as we learn more about how the virus spreads.
“It’s OK to get fatigued by the messaging, but you don’t want to get lazy on the practices of health care precautions around hand hygiene and all the things that we’ve been discussing, because that virus doesn’t care,” Rohde said. “It doesn’t care that we’re tired of hearing it or reading about it or whatever. It’s there to pounce as soon as we let our guard down.”
This story was originally published August 13, 2020 at 6:00 AM.
