The winter storm battering Texas and much of the U.S. has also dealt a blow to the coronavirus vaccination drive, delaying shipments because of poor road conditions and forcing the closure of hundreds of vaccination sites nationwide.

Hazardous weather is slowing deliveries out of a FedEx facility in Memphis and a UPS facility in Louisville that serve as distribution hubs for the Southeast.

“Due to the severe winter weather currently impacting a large swath of the country, the U.S. government is projecting widespread delays in COVID-19 vaccine shipments and deliveries over the next few days,” Kristen Nordlund, a spokeswoman for the Centers for Disease Control and Prevention, wrote in an email.

She did not detail which states and how many of the 11 million doses scheduled for delivery this week are affected.

But a slew of localities announced delays, including canceled vaccination events Tuesday in Alabama, Indiana, New Hampshire, South Carolina, Tennessee, the Chicago area and more. Missouri closed all large-scale vaccination sites through Friday. The grocery chain Publix stopped taking appointments for shots in Florida, South Carolina and Georgia, citing shipping delays. Texas said its weekly vaccine allotment wouldn’t begin to arrive until Wednesday.

“No one wants to put vaccine at risk by attempting to deliver it in dangerous conditions,” the Texas Department of State Health Services noted Tuesday in a graphic on Twitter.

In some cases, residents who nabbed elusive vaccine appointments for themselves or their family members now find themselves back at the start of their search.

Texas's independent power grid was crippled under high demand and damaging weather after a historic cold snap hit the U.S. over Presidents' Day weekend. (John Farrell/The Washington Post)

Austin resident Shana Gallagher, 26, was scheduled to receive her first dose Monday in Waco, Tex., more than 100 miles from her home — the closest appointment she could find after long stretches clicking refresh online. But when she canceled her assigned slot because of the weather, she was forced to give up her second-dose appointment, too, she said.

“I probably spent three hours cumulatively across many days and weeks, and I finally got one. It’s just going to be more of that again,” said Gallagher, who has autoimmune conditions that place her in a priority category.

She said the delay receiving the vaccine could be “life and death” for others who have to go to work in person. “For me, it’s mostly just frustrating,” Gallagher added. “But for thousands of people, it’s much more than that.”

The latest round of weather-related vaccine delays highlights a key vulnerability in the mass inoculation effort: Both vaccines authorized in the United States need to be stored at ultracold temperatures, triggering a sprint to use them within hours when they cannot.

Officials in Harris County, which includes Houston, scrambled to deploy 5,410 doses after the facility where they were stored lost power and the backup generator failed early Monday.

They distributed the vaccines to Rice University, several hospitals and the county jail to use Monday before the doses spoiled. But the rush turned out to be unnecessary: County officials said vaccine maker Moderna later assured county officials that unused vials could be returned to cold storage without losing efficacy.

“No vaccine has been spoiled or wasted, so they are being either administered or re-refrigerated,” said Rafael Lemaitre, a spokesman for the county.

Lemaitre said the county started to collect unused vials Tuesday and couldn’t say how many were used. Rice University confirmed it had none left.

The school, which did not lose power, sent an alert to its students offering fewer than 1,000 vaccines at an existing coronavirus testing site to those already on campus. All were claimed within four hours.

“It happened hastily,” university spokesman Jeff Falk told The Washington Post. “And they got them in arms, which is a good thing.”

Beyond obvious transportation problems, the winter storm disrupted other key aspects of vaccine distribution, from appointment scheduling to vaccine-temperature monitoring.

Stephen Williams, Houston’s health director, said the city hasn’t been able to administer doses since Saturday and has already canceled clinics through Wednesday.

Weather-related Internet disruptions interfered with his staff’s ability to remotely monitor refrigeration at clinic sites. That prompted police to accompany nurses to these sites on Monday to inspect refrigerators, Williams said. By Tuesday, city officials had transferred doses to a central location with a backup generator to avoid monitoring multiple sites at a time.

When sites reopen, possibly on Thursday or Friday, providers will prioritize people waiting for their second dose of the two-dose protocols. Williams said he and his staff are discussing ways to increase capacity through the weekend at major vaccination sites to make up for lost time.

Indiana, which closed scores of vaccination sites on Tuesday and Wednesday, warned residents that inclement weather is causing scheduling difficulties and urged patience while calling 211 to reschedule appointments. Tennessee, however, told residents that their local health departments would contact them to reschedule if needed.

Illinois avoided delays in vaccinations by preemptively ordering doses for its strategic stockpile, the state health department said in a news release Tuesday. As a result, the state is able to continue sending doses to providers and “would not be subject to delays due to weather in other parts of the country.”

Ohio Gov. Mike DeWine (R) said Tuesday that shipments from vaccine manufacturers were delayed by one or two days while the state was proceeding on a two-hour delay delivering 26 parcels of repackaged doses.

Despite the severe weather, he stressed that many providers with vaccine supply were going ahead with scheduled appointments and encouraged residents to check road conditions before venturing out — but not to assume that their hard-to-find slots had been pushed back.

That was a source of confusion for people around the country who weren’t sure whether their designated vaccination sites were still operating and struggled to contact them by phone.

San Antonio resident Jessica Vidal, 60, and her partner were getting ready to drive on icy roads to get their dose Monday afternoon when she reconsidered, wary of the dangerous driving conditions. They weren’t even sure whether their pharmacy was even offering inoculations because there was no information available online.

“And there was that possibility,” Vidal said. “What if we got there and there was no vaccine.”

The Biden administration is monitoring the winter storm’s toll on vaccine distribution, White House press secretary Jen Psaki said Tuesday, but she offered no details.

Psaki announced weekly vaccine allocation to states will rise to 13.5 million, a 2.5 million dose increase as supply continues to run far behind demand. The latest uptick, part of which comes from the administration’s new approach of counting the sixth Pfizer dose that can be drawn from vials with a specialized syringe, marks an overall 57 percent increase in weekly supply since President Biden was inaugurated on Jan. 20, Psaki said. Much of that increase comes from long-anticipated expansion of manufacturing capacity.

The government is also providing more vaccine directly to pharmacies, increasing the number of doses per week from 1 million to 2 million. That increase is part of a gradual expansion of the ability to Americans to sign up for inoculation directly from familiar drugstores.

Tuesday’s announcement came five days after Biden disclosed that his administration had finished an agreement with two vaccine manufacturers for an additional 200 million doses by the end of July. The government, exercising options built into contracts negotiated last year, purchased half of those doses from Pfizer and its partner BioNTech, and the other half from Moderna — the vaccines authorized for emergency use in the United States.

That purchase should make the amount of vaccine available by midsummer enough to cover every U.S. adult.

The general public can expect vaccines by early June, Anthony S. Fauci, the nation’s top infectious-disease expert, told CNN on Tuesday. Fauci said that target is later than his previous April projection because Johnson & Johnson, whose single-shot vaccine is expected to receive authorization later this month, has fewer doses than he expected.

If it is cleared, doses in the single-digit millions of that vaccine will be initially available, according to federal officials familiar with the matter. Jeff Zients, the White House’s coronavirus coordinator, told governors on a call Tuesday that the company would be able to scale production to meet its commitment of providing 100 million doses to the United States by the end of June.