As the world focuses on omicron, the delta variant is overwhelming parts of America

Beds have been full for seven weeks with a flood of mostly unvaccinated patients, a hospital official said. The hospital routinely turns down other overwhelmed facilities trying to transfer covid patients - sometimes saying no as many as 15 to 20 times a day.

The first U.S. cases of omicron have been detected in California and Minnesota - about 60 miles southeast of St. Cloud in Hennepin County, in a man who traveled to New York City last month. He was vaccinated and has recovered, health officials said.

But public health experts in Minnesota and nationwide are urging Americans not to lose sight of the fact that the overwhelming majority of the nation's coronavirus cases - and those in Minnesota - are caused by the highly transmissible delta variant. Over the past six months delta has been responsible for some of the worst spikes of the entire pandemic. It is so contagious that even states with above-average vaccination rates have seen surges - and many are bracing for cases to increase again.

George Morris, covid-19 response incident commander for CentraCare, St. Cloud Hospital's parent organization, described delta as a train going off the tracks. "We just continue to see rail car after rail car pile onto this derailment," he said.

"Omicron is potentially another train coming," Morris said. "It's a whole other train coming right behind a wreck."

Doctors and others on the front lines warn delta strikes rapidly, filling up hospitals so quickly some started rationing care for the first time in the pandemic. Vaccinated people end up infected in higher numbers when transmission is out of control. While they are unlikely to fall seriously ill, they can still spread the virus, end up with a nasty but clinically mild case they'd rather avoid or end up hospitalized if they are elderly or immunocompromised.

Even if omicron turns out to be less worrisome than feared, epidemiologists warn the U.S., particularly the Northeast and Upper Midwest, is still headed toward a winter surge fueled by the delta variant as people travel for the holidays and gather indoors in cold weather. While officials are urging Americans to get booster shots to protect themselves as much of the country heads indoors, just over one in five Americans have received them as immunity from initial shots starts to wane.

"Forget about omicron right now. We are not even handling delta well, no matter what happens to omicron," said Eric Topol, director of the Scripps Research Translational Institute. "We have the combination of elapsed time, a hyper contagious variant and relaxed mitigation. It's the perfect storm to have a surge."

Scientists expect clearer data by the end of the next week that would explain whether omicron is even more contagious than delta and more resistance to vaccines or therapeutics.

But in the meantime, they are reminding Americans that it wasn't long ago that delta was the frightening variant identified abroad during India's spring surge. Now delta is the dominant strain in the U.S. And it has remained the top threat because it is so contagious even as other variants have come and gone.

Unlike omicron, scientists have answered crucial questions about delta, including that it can be spread by the vaccinated who contract breakthrough infections and that it is 50 percent more contagious than the predominant strain last spring. While there are still outstanding questions about whether it makes people more sick, doctors have anecdotally reported having younger patients showing up to the hospital faster compared to 2020 and the Centers for Disease Control and Prevention has cited some studies suggesting delta cases are more likely to require hospitalization.

New Jersey Health Commissioner Judy Persichilli stressed delta was driving the state's uptick in hospitalizations during a Monday press briefing addressing omicron.

"I encourage everyone not to be hysterical about what we don't know about omicron, but to be really proactive in controlling what we do know, which is the delta variant is here, it's with us, it's causing increasing trends," Persichilli said.

The same protective measures that officials have long been urging still apply now: Getting vaccinated and boosted, wearing masks in crowded indoor settings and getting tested before big family gatherings.

After announcing the first known omicron case, Minnesota health officials stressed the persistent delta surge is reason enough to take precautions.

"Even without omicron, there was plenty of reason for people to take full advantage of those prevention tools," Minnesota Health Commissioner Jan Malcolm told reporters Thursday. "Omicron again is just another kind of wake-up call if we needed one."

St. Cloud Hospital is experiencing how delta can stretch hospitals to their limits. And that's before an expected spike linked to Thanksgiving travel and gatherings.

"We're at the point where we are borderline saying nobody is going to get in," Morris said of transfer patients. "And that's going to be real hard, because we're going to have people backed up in the emergency room, backed up in all of our regions, backed up at home because we're full."

The surge at the University of Michigan Health-West is stretching into a third month - the longest one of the pandemic - with no immediate end in sight.

Chief medical officer Ronald Grifka says the hospital is under strain, with health care workers testing positive and having to miss work. Many procedures have been delayed. And even though some of those procedures are considered elective, Grifka noted that deferrals can have a major impact. He gave the example of a patient falling after a hip surgery was canceled and landing in the hospital for emergency surgery.

Test positivity rates have been hovering around 20 percent, he said, suggesting the virus is still rampant and cases will continue rising after Thanksgiving gatherings. And state surveillance data suggests delta accounts for nearly every Michigan infection.

"It's here. It's still wreaking havoc in the community," said Grifka. "We can't take our eyes off delta, that's for sure."

Unlike with omicron, the U.S. has the benefit of hindsight with delta.

Delta fueled India's devastating early 2021 coronavirus surge, marked by harrowing scenes of people dying on the streets gasping for air because hospitals ran out of beds and oxygen.

That wave arrived during an optimistic time in the U.S. as Americans emerged from a dark winter surge and vaccines were becoming widely available.

"It's always not us until it is us," said Ashish K. Jha, the dean of the Brown University School of Public Health who urged Americans to treat India's crisis as an American problem. "At the very beginning it was China, but not us. Then it was Italy, but not us. Then it was us. Then it was New York, but not the rest of the country. It baffles the mind how we manage to delude ourselves into thinking it's always over there, and it's not going to hit us in our own home."

The Ozarks became one of the first delta hotspots in the U.S. last June and July. Hospitals in Springfield, Mo., warned they were treating more patients than at any point during the pandemic - a harbinger for the record shattering hospitalizations throughout the Southeast and rural West in the months ahead.

"When delta overwhelms southwest Missouri, which is not very densely populated, it's very foreboding what it can do to highly densely populated areas like the Northeast," said Steve Edwards, chief executive of CoxHealth, which operates a Springfield hospital that was battered in the summer and recently reopened a covid ward as admissions rise again.

Edwards watched in dismay as much of the country failed to heed the lessons from southern Missouri before delta tore through the Sun Belt and rest of the Midwest.

"Half the country listened and the other half listened to an ideology based on politics, religion and their sense of culture which overrode their understanding of science," Edwards said. "It kind of breaks your spirit because it's an open-book test and the answers are there."

Instead of the country uniting behind the common threat of the delta variant, it became more sharply divided as Republican governors and state legislatures focused on reining in public health measures rather than the virus itself.

Florida Gov. Ron DeSantis, a Republican, waged a war against local governments and businesses attempting to require masks and vaccines even as his state reported nearly 20,000 fatalities since the delta surge started in July. Hospitalizations soared past 17,000, an all-time peak. Texas banned vaccine mandates as the state health department reported unvaccinated Texans were 40 times more likely to die of covid-19. Overwhelmed hospitals in Alaska, Montana and Idaho were forced to ration care.

Idaho's largest health system, St. Luke's, came "very close" to having to ration care during a delta surge earlier this fall, said chief physician executive Jim Souza. He described a herculean effort to avoid that crisis: treating patients for septic shock in emergency department waiting rooms, expanding nurse-patient ratios, converting hospital spaces to fit additional beds.

Still, patient care was affected. The safety net was there, he said, but it "got a little bit threadbare."

For parts of the country that have not yet experienced a delta surge, Souza said, "do not underestimate this virus's ability to move into exponential growth. Do not underestimate what that will mean for your teams."

Perhaps one of the most important lessons from the delta surges is that highly vaccinated areas are not spared. By August, counties with above average vaccination rates still short of herd immunity were igniting as covid-19 hotspots. But places with higher vaccination rates also saw lower hospitalization rates as the vaccine succeeded at its core job of keeping people from becoming seriously ill.

New Orleans was an early test of how a highly vaccinated community can manage new waves of the surge. Officials believe breakthrough infections were a major driver of the surge, but noted hospitalization rates were much lower among city residents than residents of poorly vaccinated rural parts of Louisiana.

"It's just a numbers game: When you have a population that was 75 percent vaccinated, if everyone is exposed to delta as we probably were in some form or fashion, that's a lot of people who are going to get a breakthrough infection," said Jennifer Avegno, the city's top public health official.

The city ended up imposing an indoor mask mandate, regardless of vaccination status, and required restaurants and bars to require proof of vaccine for entry. Avegno said people in highly vaccinated communities should ignore the threat of delta at their own peril. Even if young adults with breakthrough infections are comfortable with their low risk of severe cases, they can spread it to the unvaccinated or vaccinated people who will have a harder time mounting an immune response.

"I hope our example is not unheeded," Avegno said in an interview. "Sometimes there's a tendency to cast aspersions on a particular region that got the outbreak first and say that's them, rather than saying how can we learn from their lessons so we don't have to go through the same thing."