In Louisiana, which has seen new infections skyrocket to the highest point of the pandemic, the governor implemented a statewide indoor mask mandate as hospitals are again delaying elective surgeries and limiting visitors. In Florida, which has been reporting about a fifth of all new U.S. cases, at least 10 hospitals in the Jacksonville and Orlando areas have hit their all-time peaks in covid-19 admissions. Disney World, New Orleans and Las Vegas, destinations for tourists craving a return to normalcy, are mandating masks again.

While much of the country wrestles with new masking guidance and new evidence of the dangers of the highly transmissible delta variant, public health authorities and doctors in the states hit hardest by the latest viral surge are confronting a new stage of the pandemic unlike anything they have seen.

Infections are tearing through their communities faster than before, even with significant chunks of their population immunized through vaccinations or natural antibodies from infections. Hospitals are struggling to keep up as their beds rapidly fill up with young and middle-aged unvaccinated adults.

They are illustrations of how quickly communities under assault from the delta variant can slip from normalcy to crisis mode and why public health authorities are sounding alarms even before cases in their communities surge.

“Eliminating the virus is no longer an option,” said Dave Rubin, director of PolicyLab at the Children’s Hospital of Philadelphia. “This is about trying to minimize the impact.”

Average daily new U.S. cases over the past month surged past 85,000 on Monday, surpassing last summer’s peak and now the highest since Feb. 18. Hospitals are treating around 50,000 covid-19 patients, a census that more than doubled in two weeks but remains below last summer’s levels. Deaths have risen slightly to around 370 a day but remain far below the 1,000 daily averages in early August of last year.

The delta variant has become the dominant strain of coronavirus in the United States, resulting in a rise in infections and hospitalizations. (John Farrell/The Washington Post)

Aileen Marty, an infectious-disease expert at Florida International University, said new data from the Centers for Disease Control and Prevention showing that the delta variant appears to cause more-severe illness and is transmissible by fully vaccinated people echoes how her lab has been detecting high viral loads among the vaccinated in South Florida as it battles a surge.

“Unfortunately it’s not acting in such a way it’s preventing that vaccinated person from being a transmitter,” Marty said. “We are really thinking this is going to go on through August unless there’s a massive change in behavior and vaccination rates.”

Available research has repeatedly confirmed that vaccinations still offer robust protection against serious illness and death caused by coronavirus. The latest CDC data raises concerns about the role of vaccinated people who develop uncommon infections in spreading the virus, which is what inspired recommendations for wider masking as a precautionary measure.

“Delta spreads like wildfire. But vaccines contain that fire and will eventually help to put it out,” said Aditi Nerurkar, a physician at Harvard Medical School. “For now, our shared goal must be to vaccinate everyone and avoid breeding vaccine discontentment. Vaccines continue to be the surest bet to keep people out of hospitals, ICUs and the obituary pages.”

The early-summer outbreak in sparsely vaccinated Missouri has started to level off after five weeks, suggesting the delta surges may resemble those in the United Kingdom and India, with steep spikes followed by deep plunges. But Missouri has also proved to be a harbinger of things to come for sparsely vaccinated communities struck by the delta variant — and for their better-vaccinated neighbors who still have a large number of susceptible residents.

While much of the summer surge has been concentrated in several Southern states, experts fear other states with lower vaccination rates will see their upticks in cases abruptly soar.

Rubin, who monitors coronavirus trends nationwide, said he is watching signs of emerging surges in Texas and California and potential fall spikes in Midwest states with lower vaccination rates, such as Ohio and Indiana.

He stressed that the delta variant, while often primarily blamed for the surge, is more easily spreading and replicating in a country that has almost fully reopened, unlike in earlier stages of the pandemic.

“We are seeing the natural evolution of a virus without any masking or distancing,” Rubin said. “It’s a completely different environment for transmission.”

There has been little talk of states again closing bars, clearing out stadiums and shutting down schools. Political leaders have largely responded to rising infections by doubling down on their vaccination pushes.

Their efforts have started to escalate over the past two weeks, with a wave of vaccination mandates for the federal and local government workforces and new face-covering recommendations and requirements. Masks, while reviled by many conservatives, remain a preferred tool because they limit the spread of the virus while allowing the economy to remain open.

But federal health officials worry many of the places in most need of mask mandates, including in the South, will not adopt them, according to two Biden administration officials who spoke on the condition of anonymity because they were not authorized to comment publicly. Florida Gov. Ron DeSantis (R) has repeatedly said he opposes new restrictions or mask mandates and is working to block schools from requiring face coverings.

For communities in the throes of summer surges, it is hard for leaders to predict whether they will burn through unvaccinated communities quickly before dissipating or stretch longer.

Arkansas, battling a surge that appears to have spilled over from Missouri in late June, continues to confront one of the fastest rates of new infection. Hospitals in northwestern Arkansas reported treating 163 patients as of Tuesday, higher than the winter peak. They are bracing for things to get worse — particularly because social distancing measures led to little to no flu or pneumonia last year.

“I expect through the fall and winter it’s going to be a big strain on not just our health system but really all health systems,” said Eric Pianalto, president of Mercy Hospital Northwest Arkansas.

‘These are the darkest days of the pandemic’

Melissa Childs hoped to escape the virus surge battering central Missouri to celebrate her 50th birthday in New Orleans.

She instead arrived last week as Louisiana became the nation’s latest epicenter, with average new daily cases reaching all-time highs of 4,000 by this week.

“It’s a tenfold increase in just one month, and it’s not showing any signs of stopping,” said Susan Hassig, an epidemiologist at Tulane University, noting that rising hospitalizations are now mirroring levels from March 2020, when New Orleans became one of the first metropolitan areas overwhelmed by the virus. “That to me is really, really scary.”

Childs and her 17-year-old daughter, both vaccinated, were the rare tourists following the mayor’s mask advisory — put in place before the state mandate — last week while wandering the French Quarter. Bars and restaurants were packed with unmasked patrons while hundreds strolled through streets sipping to-go drinks and posing for photos.

At one point, mother and daughter stepped away from the Bourbon Street crowds to take off their masks, which had become uncomfortable in the 90-degree heat. But after seeing how the surging delta variant killed young people in Missouri, Childs was willing to deal with a little discomfort.

“I work at a school, so it’s important to me to stay safe for the kids,” she said.

Joseph Kanter, Louisiana’s state health officer and medical director, attributed the explosion of cases to an above-average presence of the delta variant earlier in July that fueled rapid transmission; the state’s stubbornly low 37 percent fully vaccinated rate; and punishing summer heat driving people indoors.

“This delta variant has proven much more aggressive than anything we have faced before,” Kanter said in an interview. “We’ve led the country in cases before, and it’s frustrating to be back here.”

Gov. John Bel Edwards (D) issued a statewide indoor mask mandate Monday given that cases continue to rise, “threatening the ability of hospitals to deliver care,” he wrote on Twitter.

Catherine O’Neal, a hospital chief medical officer in Baton Rouge, encouraged citizens on Aug. 2 to get vaccinated. (Office of Gov. John Bel Edwards)

Our Lady of the Lake Regional Medical Center in Baton Rouge, the state’s largest private hospital, announced Monday it was under “immense pressure,” with 155 covid-19 patients — the highest since April 2020. About half of the patients were under the age of 50 and 80 percent were unvaccinated.

“When you’ve come inside our walls, it’s quite obvious to you these are the darkest days of the pandemic,” Catherine O’Neal, the hospital’s chief medical officer, said at a news conference urging people to wear masks. “We are no longer giving adequate care to patients. That has also stopped.”

In an earlier interview, O’Neal told The Washington Post that officials were scrambling to keep up staffing by redeploying nurses to hospitals, calling people to return from vacation and pausing non-urgent surgeries to save bed space.

“The difference right now is the delta variant. It is so infectious, and it is so severe, and it is infecting people who I probably would have told a year ago, ‘You’re going to be fine,’” she said. “This year’s virus has shown us quite clearly you don’t know whether you are going to be okay.”

The vaccinated appear to be playing a much smaller role in Louisiana’s spread.

State officials said last week that 10 percent of hospitalized covid-19 patients statewide were vaccinated, with a median age of 73. O’Neal said even older vaccinated patients at Our Lady of the Lake tend to be in better shape but are admitted for close monitoring because of their fragile conditions.

New Orleans is still reporting new coronavirus cases at winter levels despite its above-average vaccination rate. But Kanter said the city is seeing comparatively fewer hospitalizations and severe health outcomes than poorly vaccinated communities.

In the Marigny neighborhood, eight out of 25 staffers at the Paladar 511 restaurant tested positive for the coronavirus earlier in the summer. All but one were vaccinated.

“That was kind of just an eye-opening thing,” said Emma Jane Kulowski, 26, the restaurant’s manager. “It was a little bit disheartening after so long being cautious and trying to do the right thing, even without clear guidance.”

After a costly shutdown, the restaurant reopened with a big supply of at-home rapid tests and masks required for even vaccinated staffers. Because of the summer heat, Paladar has held out on bringing back outdoor seating like what it offered during earlier waves, but locals have been asking for the option as cases surge.

Louisiana also offers some hope for a path out of the pandemic: Vaccine dose administrations have jumped 42 percent over the past week, according to Washington Post data, a sign the summer surge is galvanizing people to protect themselves and their communities. While experts say the most recent vaccination upticks are probably too late to stop the ongoing spike, they could stymie fall and winter surges.

Lee Joseph, a 41-year-old chef in New Orleans, is among those moving off the fence. The unfolding crisis made him rethink his reliance on masks alone as protection.

“At first, I wasn’t going to do it,” Joseph said while on a cigarette break from his job cooking shrimp and grits, gumbo and alligator po’ boys. “But this stuff here is getting worse and worse.”

‘I’m still going to live my life’

Florida was preparing for another summer spike, especially after getting hit hard during last year’s summer Sun Belt surge. But this one is worse: Florida over the weekend reported its largest-ever single-day increase in new coronavirus cases and a record for hospitalizations, with more than 10,000 patients. The record-high admissions come despite heavy immunization rates among senior citizens, who are more likely to end up in a hospital bed.

“What’s extraordinary is the speed at which we are currently seeing new cases,” said Vincent Hsu, an infectious-disease physician at AdventHealth, which is reporting record-high admissions across Central Florida hospitals. “We have to be prepared for a long surge, a long siege, and continue to prepare like there will be more cases, because we just don’t know.”

Orange County, which is served by AdventHealth, has stood out, with new daily infections crossing 1,000 for the first time and the highest rates of positive test results to date. Orange County Mayor Jerry Demings (D) declared a state of emergency last week and urged everyone to wear masks indoors, as well as mandating non-unionized county employees to get vaccinated or face termination.

Even though half of its population is fully vaccinated, in line with the state and national average, Orange County is also a major tourist destination, drawing millions to Disney World, Universal Studios and SeaWorld.

The rapid increase in Orange County led to the cancellation of a 5,000-person conference hosted by the Association of PeriOperative Registered Nurses. The association’s leader made the decision after watching the mayor describe the spike as a “crisis” at a news conference, shifting to a virtual conference instead.

“The nurses have had just a terrible year where they have watched patients die and haven’t been able to see their relatives,” said Linda Groah, the association’s chief executive. “They’re burned out, and we were all so looking forward to putting some joy back in their lives.”

“I did not want to risk holding a superspreader event,” she said.

But not everyone plans to carry on with an abundance of caution. While Disney World announced a mask mandate for anyone over the age of 2 and a vaccination mandate for its employees, Universal Studios and SeaWorld are only encouraging masks. Interviews at an outlet mall near Universal Studios showed that masking was not going to become any less controversial, even after a new surge and new government recommendations.

Becky Evans, a 43-year-old server from Indiana on a beach trip, lamented that “your face breaks out” from having a mask on and that “breathing is not as easy.” She and her husband did not rethink their vacation plans because of the delta variant.

“I’m not going to let it ruin my life,” Evans said. “I’m still going to live my life, still going on vacation.”

Cusick reported from New Orleans. Eric Adelson in Orlando and Yasmeen Abutaleb and Jacqueline Dupree in Washington contributed to this report