The person-to-person spread of the coronavirus in the Houston region would peak in two weeks and burn out by mid-May if the stay-at-home order invoked Tuesday is continued until then, according to modeling by local scientists.

The modeling, which informed Harris County Judge Lina Hidalgo’s order, considered the effect on the spread of COVID-19, the illness caused by the virus, if she’d taken the stringent intervention immediately or waited a week or two weeks to act. Spread would increase exponentially had she waited, it found.

“From our modeling, it was clear that waiting is not a good thing,” said Eric Boerwinkle, dean of the University of Texas School of Public Health, who conducted the study with a biostatistician at that Houston institution. “The numbers are sobering, but the message is clear: early intervention is better than late intervention and more stringent intervention is better than less stringent.”

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UTHealth released the modeling data as the city of Houston began gearing up — scouting sites that easily can be converted into medical centers, looking for hotel rooms for COVID-19 patients who cannot isolate at home or in a hospital — for what’s expected to be the next, worse phase of the pandemic: the dramatic escalation in cases.

The efforts also came a day after Hidalgo’s order closed most businesses and directed residents to stay put, except for groceries and errands. She said she was heeding the warnings of health experts, who’d called for the order to prevent Houston hospitals from being overwhelmed with cases.

The UTHealth modeling, shared with city and county officials Monday, provided data backing the warnings. It found that intervening immediately would limit the number of cases in the region to a peak at about 150 a day around April 7 and stop the spread around May 12. In that time, the cumulative total of cases would reach nearly 3,500, it found.

Cases would peak at more than 1,000 a day on April 15 if Hidalgo had waited a week and more than 6,600 a day on April 22 if she’d waited two weeks. Transmission would last until May 29 under the first scenario and June 16 under the second.

All three of the scenarios are based on the premise the restrictions would continue until mid-May. Hidalgo’s order is scheduled to expire April 3.

The UTHealth researchers are currently conducting modeling research to look at the effect on COVID-19’s spread if the restrictions are lifted after two weeks and after one month. Boerwinkle said he hoped to have that data available by the end of the week.

The city’s search for candidates for makeshift medical centers includes now-vacant hospital buildings and other facilities that could be used to treat patients if — or when — area hospitals reach capacity and become overwhelmed.

“We’re looking at all potentially available resources,” Mayor Sylvester Turner said.

Turner said the city also is finalizing lease agreements with two hotels for around 180 rooms that could house patients who need to isolate themselves. Some of those rooms, he said, could be used for the city’s homeless population as well.

The efforts were aided by the city’s acceptance Wednesday of a $5 million health disaster grant from the U.S. Centers for Disease Control and Prevention. The money also will be used to boost administrative health staff, provide behavioral and mental health support services, establish quarantines and buy equipment for testing, according to the agenda item presented to councilmembers Wednesday.

The plans reflect the view, reinforced by the UTHealth research, that the pandemic will worsen before it begins to improve. Officials and hospital executives have closely monitored the situation in New York City, whose health care system is under increasing stress amid an outbreak there.

Currently, most hospitals in Houston are not at capacity, though some said they already have little room to spare. The recent cancellation of elective procedures, among other moves, has helped free up some space.

“It’s pretty much a full house all the time,” said Bryan McLeod, a spokesman for Harris Health System, which operates the county’s Ben Taub and Lyndon B. Johnson safety-net hospitals.

He said the system was at 87.3 percent of its capacity at the end of February, though most of the empty beds are not for critical adult care. The occupancy level will be recalculated at the end of March.

The Houston Methodist system, which operates eight hospitals, is at 71 percent capacity systemwide, a spokeswoman said. Memorial Hermann, which has 17 hospitals, is at 60 percent.

Gov. Greg Abbott announced a measure Wednesday to help increase bed space, waiving certain licensing rules to allow facilities with pending applications, and those that have been closed for less than 36 months, to come online.

Also Wednesday, the Texas Association of Freestanding Emergency Centers issued a statement that their facilities stand ready to help ease the burden.

Boerwinkle and UTHealth colleague Momiao Xiong used artificial intelligence to create the modeling system. A paper on its use to analyze the virus’ spread globally is under review by a top-tier journal.

There is no planned publication of the local research, which focuses on not just the Houston area but other metropolitan regions in Texas, because it was done as a service to those communities, said Boerwinkle. The modeling, originally based on the virus’ spread in China and Italy, incorporated the U.S. spread as well.

Boerwinkle, former chair of the UT public health school’s department of epidemiology, human genetics and environmental health said the Texas coronavirus picture looked good, at least compared to New York and California, when the team analyzed it March 16th. But by March 23rd, he said, it had taken a significant turn for the worse.

“That’s what got the mayor’s and judge’s attention,” said Boerwinkle.

Under the modeling, had Hidalgo waited a week, the cumulative number of cases would climb to nearly 23,800. If she’d waited two weeks, the number of cases would exceed 153,000.

Nine counties — Harris, Brazoria, Fort Bend, Galveston, Montgomery, Austin, Chambers, Liberty and Waller — constituted the Houston region under the modeling.

Boerwinkle said if the restrictions remain in place until mid-May, he’s confident the community will have gained enough immunity to the virus that their lifting would result in no more than a small second wave and even smaller third wave, not a major resurgence.

Boerwinkle added that he understands that the burden on health care setting is just one aspect of the issue, that the social fabric and economy are also considerations.

“The intervention taken Tuesday is what’s necessary to stem the tide,” said Boerwinkle. “But area residents should know this isn’t like hunkering down for the weekend for a hurricane. This is longer term than that.”

todd.ackerman@chron.com

dylan.mcguinness@chron.com