Advertisement

newsPublic Health

Dallas County could see summer surge in COVID-19 cases, UTSW scientists say

Experts say better social distancing needed to avoid spike

Dallas County could see 800 new COVID-19 infections each day by early July — about three times the current level — if people continue interacting as much or more than they are now, according to new forecasts from disease experts at UT Southwestern Medical Center.

The projections come as some businesses have begun operating at limited capacity and gyms and manufacturing plants are set to do so Monday.

The new forecasts are some of the most detailed yet for the region. The researchers note that the projections can change and, like weather forecasts, are not perfect predictions of what is coming.

Advertisement

“The model really is further validation that when you [reopen too soon], bad things happen," said Dallas County Judge Clay Jenkins, who addressed the forecasts at a news conference Thursday.

D-FW Public Health Alerts

Get the latest coronavirus and public health updates.

Or with:

“We should know very quickly if these projections are accurate,” said Dr. John Carlo, a former medical director of Dallas County’s health department and a member of the Texas Medical Society’s COVID-19 Task Force. If they are, officials could consider reimposing stronger physical distancing measures, he said.

The UT Southwestern scientists, led by infectious disease specialist Dr. Trish Perl, also offer a county-by-county picture of how the epidemic expanded early on in North Texas and then slowed to various degrees in each county while social distancing orders were in effect.

Advertisement

“It’s a nice addition to the modeling scenarios we have because this one is looking specifically at the effect of social distancing on disease transmission,” Carlo said. “I think it’s a good initial analysis that hopefully we can use to make some judgment calls.”

More mobility, more disease

In some ways, the forecast is not surprising: Social distancing keeps transmission low; relaxing it leads to more infection. Even so, the new projections illustrate its dramatic effect.

Advertisement

Dallas County issued a stay-home-order March 23; Texas followed a week later. Had officials waited much longer, Dallas County could have had 93,000 cases by early May, according to UT Southwestern.

The projection of 800 new cases per day in July is based on current social distancing measures, which researchers estimate are 60% effective at curbing the spread of the virus. If measures weaken to be 57% effective, the forecast reaches 800 cases by June.

In the reverse, if social distancing measures tighten up and become 65% effective, cases would roughly hold steady for the rest of the year. Increasing to an effectiveness of 69% would tip the epidemic into a decline, although it would still continue at least until year’s end, where the forecast stops.

As recently as mid-April, residents of Dallas, Tarrant, Collin and Denton counties were moving around very little, according to mobile phone data the researchers analyzed.

“It speaks to how, initially, people took this quite seriously,” said UT Southwestern’s Perl.

But beginning in the third week of April, even before stay-at-home orders expired, visits to non-essential stores, encounters between people, and the overall distance that people traveled grew.

Now that businesses are reopening, mobility is still swinging upward.

Advertisement

Because mobility correlates with new infections, the researchers said they will follow the trends closely.

Future uncertain

The UT Southwestern scientists also estimated whether the disease has expanded or contracted over recent weeks, using a value that measures the extent to which the virus is spreading.

If the number is greater than 1, the disease is expanding. If it’s less than one, it’s shrinking.

Advertisement

Before the statewide order went into effect April 1, the value in all four counties was greater than 2. It dropped to about 1 in early to mid-April, then slightly fluctuated. In Dallas County, it fell below 1 for the first time in late April.

If that had continued, the disease could have been pushed into a sustained decline. The most recent values are now just over 1 in all four counties, according to UT Southwestern’s calculations.

Because the virus is so new, researchers have not figured out which physical distancing measures work best. For instance, it’s unclear what the effect will be of Gov. Greg Abbott’s order that allowed restaurants, barbershops and salons to open with restrictions earlier this month.

Advertisement

“We’ve never been in this situation before,” said Spencer Fox, who co-leads the University of Texas at Austin’s COVID-19 Modeling Consortium. He said the group is seeing signs that reopening the state is causing the epidemic to expand again. “So, we expect if those trends continue that reopening will continue to fuel the epidemic.”

On Thursday, Dallas County reported 235 new cases of COVID-19, bringing the total number of confirmed cases to 6,837. Thursday’s number is in line with what Dallas County has seen for the past 10 days, Judge Clay Jenkins said.

The city of Dallas, meanwhile, reported that as of Wednesday, 65 percent of local hospital beds were full — the highest rate yet during the pandemic, based on city statistics. Two-thirds of ICU beds were full. Both figures have increased slightly over the past month and a half.

Advertisement

Texas broke two grim records Thursday — 1,448 new cases and 58 deaths. That brings the total number of Texas deaths linked to the virus to 1,216.

Testing for the virus was up sharply, however. Texas reported a record 49,000 tests Wednesday and almost 36,000 on Thursday. The previous high was about 29,000 and daily tests had been averaging closer to 17,000.

Officials in the state health department and the governor’s office did not respond to requests for comment Thursday about UT Southwestern’s forecasts.

Fox added that it’s difficult to predict the effects of reopening on the future spread of COVID-19. “We don’t quite know what’s going to happen, but it would be prudent to continue acting as if we’re in the middle of a pandemic, which we are.”

Advertisement

A previous version of this story incorrectly stated the number of Texas coronavirus cases reported Thursday as 1,148. The correct number is 1,448.

Connect with needs and opportunities from Get immediate access to organizations and people in the DFW area that need your help or can provide help during the Coronavirus crisis.