LAS VEGAS >> Fifteen months after the pandemic transformed Las Vegas from flamboyant spectacle to ghost town, Sin City is back.

Tourists are streaming in again, gambling revenue has hit an all-time high, the Las Vegas Strip has its first new casino in a decade, and big concerts are starting at a gleaming new stadium. Plexiglass panels installed to separate gamblers at the poker and blackjack tables have largely been removed, the world-famous buffets are reopening, and nightclub dance floors are packed.

Vice President Kamala Harris was set to visit Saturday for what the White House is calling the “America’s Back Together” tour celebrating progress against the virus.

But that progress is threatened: Nevada this week saw the highest rate of new COVID-19 cases in the country, hospitalizations are on the rise again, and the highly contagious delta variant has become the most prevalent form of the virus in the state, adding urgency to the campaign to get more people vaccinated.

Still, in a place where the economy runs on crowds and uninhibited behavior, a return to pandemic-related restrictions and mask requirements seems to be off the table.

Inside the casinos, guests are not required to wear masks if they are fully vaccinated, but employees do not appear to be asking anyone for proof.

“It seems like everything is opening back up, getting back to normal,” Teresa Lee, a 47-year-old tourist from Nashville, Tennessee, said Thursday as she stood on the Strip, looking out over the fountains in front of the Bellagio casino.

Lee said she is vaccinated and felt safe in Las Vegas because she read about the casinos’ efforts to get their workers and their families vaccinated.

Tyler Williams, a 22-year-old from Eugene, Oregon, said it didn’t feel as if there was a pandemic anymore because “people are everywhere.” He said he had seen hardly anyone with a mask apart from a few foreign tourists and felt no need to wear one himself, because he is vaccinated.

Las Vegas fully reopened and lifted restrictions on most businesses June 1, though many casino-resorts had already returned to 100% capacity before that with approval from state regulators. Visitor numbers, while not at their pre-pandemic highs, have grown by double digits four months in a row.

Shows and fireworks are scheduled for the July 4 weekend, and the new 65,000-seat Allegiant Stadium where the NFL’s relocated Raiders will kick off their season this fall was set to host its first major concert Saturday, by electronic dance music star Illenium. It will be followed by a full-capacity show from Garth Brooks next weekend.

Over the past two weeks, Nevada’s diagnosis rate of 190 new cases per 100,000 people was higher than that of Missouri, Arkansas and Wyoming — all states with lower vaccination levels — and the state public health lab found the delta variant in almost half the COVID-19 cases it analyzed.

Also, the number of patients hospitalized with the virus has grown 33% over the past week, according to the Centers for Disease Control and Prevention, though the levels are far below what they were in December, when hospitals were near capacity.

State biostatistician Kyra Morgan said Friday that the spike in cases might be attributable to the full reopening of the state and city in June and that the return of crowds and big events on the Strip could cause the increase to continue.

“If we know anything about COVID, we know that when people are gathering in close proximity to one another in large volumes, that is the recipe for COVID transmission to increase,” Morgan said.

State and local officials said that almost all the new cases and hospitalizations involve unvaccinated people and that the best way to attack the problem is by getting more shots in arms. Nevada has fully vaccinated 45% of those 12 and older, well below the nationwide level of 55%, according to the CDC.

“We are a state of skeptics when it comes to vaccines,” Morgan said. “We have a lot of anti-vaxxers, frankly, in the state of Nevada.

State and local officials, who in May went so far as to hold a vaccine clinic at a strip club, said they are trying to find more ways to persuade people, including the launch of a cash raffle.

Democratic Gov. Steve Sisolak, who took the unprecedented step of shuttering casinos for 11 weeks last year when the pandemic started, said Thursday he will ask for help from the COVID-19 response teams that the Biden administration is dispatching to boost testing and vaccinations in communities with outbreaks.

Sisolak’s office did not respond to questions about whether he is considering reimposing mask mandates or other restrictions, but Las Vegas-area officials say they are following the CDC’s guidelines, which say it is safe for fully vaccinated people to go mask-free.

“At this this point, there is no discussion about increasing restrictions to the business and social life here in Clark County,” said Dr. Fermin Leguen, chief health officer in the Las Vegas area. “Getting better numbers in immunization is the solution for this problem at this point.”