The arrival of the omicron variant of the coronavirus in the U.S. has health officials in some communities reviving contact tracing operations in an attempt to slow and better understand its spread as scientists study how contagious it is and whether it can thwart vaccines.In New York City, officials quickly reached out to a man who tested positive for the variant and had attended an anime conference at a Manhattan convention center last month along with more than 50,000 people. Five other attendees have also been infected with the coronavirus, though officials don't yet know whether it was with the omicron variant."As for what we learned about this conference at the Javits Center and these additional cases, our test and trace team is out there immediately working with each individual who was affected to figure out who else they came in contact with. That contact tracing is absolutely crucial," New York Mayor Bill de Blasio said.Once a global epicenter of the pandemic, New York has the country’s biggest contract tracing effort. The city identified four omicron cases Thursday, and a fifth was discovered in nearby Suffolk County on eastern Long Island.The variant has been detected in a handful of other states so far, including California, Colorado and Hawaii.Contract tracers have been busy in Nebraska after six cases of omicron were confirmed Friday. One of the people had recently returned from a visit to Nigeria, and the other five were close contacts of that person.In Philadelphia, officials were working to track down contacts of a man in his 30s who is Pennsylvania’s first resident infected with the variant, the city’s Department of Public Health said.And in Maryland, officials were rushing to trace, quarantine and test close contacts of three people from the Baltimore area who are the first known cases in the state. Two are from the same household, including a vaccinated person who recently traveled to South Africa, and the third has no recent travel history and is unrelated to the other two.Dr. Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials, said "more and more" contact tracing efforts are expected in the coming days, in part because of the uncertainty about how effective vaccines and treatments like monoclonal antibodies will be against omicron.Contact tracing is a vital tool in the pandemic response, allowing health departments to notify people who had close contact with an infected person and slow the progression of COVID-19."Contact tracing can give us information about how it’s spreading and hopefully break chains of transmission to stop clusters and outbreaks, or at least delay them until we know more and understand what our next steps need to be," said Crystal Watson, a senior scholar at the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health.While much is still unknown about the variant, early reports are raising alarms. New COVID-19 cases in South Africa, which first alerted the world to omicron last week, have burgeoned from about 200 a day in mid-November to more than 16,000 on Friday.Some of the U.S. cases involve people who hadn’t traveled recently, meaning the variant was likely already circulating domestically in some parts of the country.In New York, the three-day anime festival in November is presenting a staffing challenge for tracers due to the large number of attendees. The one known omicron infection involved a man from Minnesota.Officials cautioned against linking the other five coronavirus cases directly to the event."The really important point here is that’s five cases from a denominator of tens of thousands of people at this conference. And furthermore, we’ve not established any sort of link between those five cases and widespread transmission at the conference," said Ted Long, executive director of the NYC Test & Trace Corps, which runs the city’s contact tracing program.Proof of vaccination was necessary for admission, as mandated by city law, and masks were also required.Officials said they had reached all 36,500 convention attendees, vendors and exhibitors for whom they had contact information, via email, text message or phone call. But they decided it wasn't necessary to contact every single attendee since the infected man did not appear to have close contacts based in New York.In Minnesota, meanwhile, officials are investigating "a circle of contacts" for the man believed to have been infected at the conference, said Kris Ehresmann, the state’s infectious disease director."Part of the reason we did indicate where he had been — the anime convention in New York — is because there were so many people that attended that event. It would not be possible for him or really anyone to identify everyone that they were potentially in contact with,” Ehresmann said.Amid the surge of the delta variant, health investigators across the U.S. became overwhelmed and scaled back contact tracing operations, finding it nearly impossible to keep up with the deluge of new infections, administer vaccines and also do tracing at the same time.Many health officials ultimately focused on exposures at schools or potential super-spreader incidents where large numbers of people were at risk of exposure.Dr. William Schaffner, a professor of infectious diseases at the Vanderbilt University School of Medicine, expects that will ultimately happen with omicron."Contact tracing and sequencing will allow us to paint with a broad brush," Schaffner said. "But we won’t be able to track it down to each and every case, and at a given point, when you know it is here and spreading, why do we need to do that?"___Associated Press writer Dave Kolpack contributed from Fargo, North Dakota.

The COVID-19 comeback across the U.S. is putting pressure on hospitals at a time when some of them are busy just trying to catch up on surgeries and other procedures that were put on hold during the pandemic.With the highly contagious delta variant spreading rapidly, cases in the U.S. are up around 70% over the last week, hospital admissions have climbed about 36% and deaths rose by 26%, the Centers for Disease Control and Prevention said Friday.Some hospitals are reporting record or near-record patient volumes. But even for those that aren't, this round of the pandemic is proving tougher in some ways, hospital and health officials said. Staff members are worn out, and finding traveling nurses to boost their ranks can be tough."I really think of it as a war and how long can you stay on the front line," said Dr. Mark Rosenberg, president of the American College of Emergency Physicians. "And how many times do you want to go back for another tour of duty. Eventually, you just don't want to do it."Also, many hospitals were busy even before the surge began, dealing with a backlog of cancer screenings, operations and other procedures that were put off during the winter surge to free up space and staff members, according to health care leaders."Eventually you have to pay the piper, and those things have now built up," said Dr. James Lawler, who is one of the leaders of the Global Center for Health Security at the University of Nebraska Medical Center in Omaha.The fear now at some hospitals is that they might have to postpone non-COVID-19-related care again — and risk the potential health consequences for patients.Dr. Laura Makaroff, senior vice president for prevention and early detection for the American Cancer Society, said cancer screenings dropped during the outbreak and have yet to return to normal levels in many communities. She warned that delays in screenings can result in cancers being detected at more advanced stages of the disease.COVID-19 deaths and newly confirmed infections across the U.S. are still dramatically lower than they were over the winter. But for the first time since then, cases are rising in all 50 states. And the nation's vaccination drive has slowed to a crawl, with only about 48% of the population fully protected.CDC Director Dr. Rochelle Walensky warned that the outbreak in the U.S. is becoming "a pandemic of the unvaccinated" because nearly all hospital admissions and deaths are among those who hadn't been immunized. One of the most overwhelmed areas of the country is Springfield, Missouri, where public health officials begged the state this week to transform a dormitory, hotel or another large space for the care of less seriously ill COVID-19 patients so that the city's two hospitals can focus on the sickest.Mercy Springfield and Cox South have seen a seven-fold increase in coronavirus patients since late May, with Mercy treating pandemic-high numbers and Cox expected to break its own record next week.In Florida, UF Health Jacksonville is talking about setting up tents in the parking lot to help with the overflow after the number of COVID-19 in-patients doubled to 77 over the past couple of weeks. Chad Neilsen, director of infection prevention, said the hospital expects to surpass its January high of 125 COVID-19 in-patients in the next few weeks. Before the rise, the hospital had begun a push to bring back patients who had delayed care amid the pandemic. Now it is discussing canceling procedures, Neilsen said. "To be telling someone, 'Sorry, we have to delay your hip surgery or your procedure because we have too many COVID patients who are largely unvaccinated,' it is just not what we signed up to do in health care," he said. In Georgia, Augusta University Medical Center is "busting at the seams" as it handles medical procedures postponed because of the pandemic and deals with a spike in respiratory illnesses that usually hit in the wintertime, said Dr. Phillip Coule, chief medical officer. COVID-19 hospitalizations also have started inching up to around eight or 10 patients, from lows of one or two a day. While the numbers still remain far below the peak of 145 in January, Coule said he is watching the situation closely."In some ways, I feel like we are a lot better off than we were before," he said, noting that the staff is safer because of vaccinations. "In other ways, it worries we if we have to defer routine care again what the outcome will be."In California, Los Angeles County will again require masks indoors, even in people who have been vaccinated. Over the past three weeks, COVID-19 cases have doubled across Kaiser Permanente's 36 California hospitals, to more than 400. Dr. Stephen Parodi, who helped develop the surge plans for Kaiser Permanente's hospitals, said he is confident they can handle the influx, noting that the total is still less than 20% of the January peak. But he said the hospitals already were busy with people showing up at emergency rooms with more severe illnesses than they would have had if the problems had been detected sooner. "At some point, illness doesn't wait for us," he said. "The ability to defer additional care when you have already deferred for a year, year and a half, is just simply not an acceptable option."