Balancing on one leg for 10 seconds may predict likelihood of living ...

You're twice as likely to die in the next decade if you're unable to balance on one foot for 10 seconds, according to a new study.

Conversely, the study suggests that your ability to balance on one foot points to longer life expectancy.

The peer-reviewed study conducted by Brazilian researchers, published Tuesday in the British Journal of Sports Medicine, determined that a person's balance ability can be preserved into the sixth decade of one's life – meaning it's more broad of an indicator of life expectancy across age ranges than aerobic fitness, flexibility or muscle strength.

Dr. Claudio Gil Soares de Araújo, the lead author of the study and a sports and exercise physician at the Exercise Medicine Clinic Clinimex in Rio de Janeiro, said poor balance is linked to frailty in older adults and one's musculoskeletal fitness is a prime indicator of declining health.

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"If you are younger than 70 years, you are expected (as the majority of those at that age) to successfully complete the 10 seconds," Araújo told USA TODAY in an emailed statement. "For those older than 70 years of age, if you complete it, you are in better static balance status than your age-peers. ...The advantages of the 10s OLS test include the fact that it is simple and it provides rapid, safe and objective feedback for the patient and health care providers regarding static balance."

In conjunction with suggesting regular doctor visits feature a balance test, Araújo recommended that people try a 15-second balance test of their own during their morning routine when they're brushing their teeth at home, to use as a barometer for their well-being.

Researchers in the study zeroed in on 1,702 participants from ages 51 to 75 for the study, with the average age set at 61. Their first checkup – study participants were tracked starting in 2008 – collected data on their weight, waist size and measures of body fat. Only individuals who could walk steadily were included in their analysis. Then, the participants were all asked to stand on one leg for 10 seconds without holding onto anything for support. One in 5 failed the test. Each participant got three tries to put the back of their other foot on the weight-bearing leg, which could be barefoot or with a proper tennis shoe on.

The inability of participants to pass the balance test increased with age, while those with weight problems or diabetes were more likely to fail. The study's finalized research factored in age, sex, BMI, history of heart disease, hypertension, diabetes and high cholesterol. The final results determined that the risk of death within a 10-year span was 1.84-fold higher in participants who failed the balance test versus those who passed it.

The test has its limits, Araújo noted: "This is an observational study, and as such, can’t establish cause. As participants were all white Brazilians, the findings might not be more widely applicable to other ethnicities and nations, caution the researchers."

Take vitamins and supplements? You may be wasting your money ...

Americans spend billions on vitamins, multivitamin and mineral supplements for their health, but a review of numerous studies concluded there is little to no evidence some of those supplements prevent heart disease, cancer and death.

The report, released by the U.S. Preventive Services Task Force on Tuesday, concluded that "current evidence is insufficient" to determine whether vitamins and supplements actually help or hurt your health, based on 84 studies, 52 of which were done since the task force last updated their guidelines in 2014. Vitamins and supplements examined included vitamins A, B, C, D and E, as well as calcium, magnesium, beta carotene, folic acid, selenium, zinc and other multivitamins.

"Our recommendation is neither for or against taking vitamins, minerals, or combinations of those nutrients. We just don't have enough evidence," Dr. John Wong, a primary care clinician in the Department of Medicine at Tufts Medical Center who was involved in the report, told USA TODAY.

While researchers said they don't have enough evidence to prove taking supplements provides any benefits, there have been numerous studies suggesting a lack of benefits. A 2018 study found that multivitamins, vitamin D, calcium and vitamin C don't improve heart health.

Study: Balancing on one leg for 10 seconds may predict likelihood of living or dying

The finding that most of the products didn't have any benefits applied to "otherwise healthy, nonpregnant adults" or "children, persons who are chronically ill, are hospitalized or have a known nutritional deficiency."

However, people who are pregnant or planning to be pregnant, should take a daily supplement containing 0.4 to 0.8 mg of folic acid, the task force suggests.

In fact, one supplement, beta carotene, was found to be more harmful than beneficial; the use of it to prevent cardiovascular diseases or cancer actually increased the chances of lung cancer and death. The task force also "specifically recommends against the use" of vitamin E because it likely has no benefits.

The findings come as over half (52%) of surveyed Americans say they take at least one dietary supplement and nearly one-third (31%) of Americans say they use a multivitamin-mineral supplement. The report said the U.S. spent nearly $50 billion on dietary supplements in 2021.

"If you ask them why, most people say, 'to maintain or improve their overall health,'" Wong said.

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The task force acknowledged it makes sense people would take vitamins and supplements in hopes of health benefits, as some deficiencies may lead to illness.

But experts agreed the best method to maintain good cardiovascular health and cancer prevention is a balanced diet and frequent physical activity. A 2019 study from Tufts University concluded the right amount of vitamins and minerals can lower your risk of early death, but they should come from food and not supplements.

"The recommendation across all organizations with regard to multivitamins and minerals is to eat a balanced diet, and then the emphasis tends to be on plenty of fruit and vegetables and less processed foods," Wong said.

Wong added people should consult with their health professionals to determine if any vitamins and supplements are worth taking. He said this recommendation should also serve as a call to action for further research into proving the official benefits and risks for each vitamin and supplement.

Follow Jordan Mendoza on Twitter: @jordan_mendoza5.

Study identifies potential biomarker for SIDS, but a test for it is a long ...

(CNN) Australian researchers say they've identified one potential biomarker for sudden infant death syndrome, known as SIDS, but experts caution that it's just one piece of the puzzle.

About 3,400 babies die from SIDS in the US each year. There is no immediate or obvious cause of death, according to the US Centers for Disease Control and Prevention . Experts don't know which babies are at risk for SIDS or what causes it.

For their study, published May 6 in the journal eBioMedicine , the researchers measured levels of an enzyme called butyrylcholinesterase (BChE) in blood samples from 67 newborns who died of SIDS and other unknown causes between 2016 and 2020. They compared these levels with those in the blood of 655 babies in a control group and found that the children who died of SIDS had significantly lower BChE levels than living children or those who died of other causes.

SIDS usually happens when a child is sleeping. Experts have speculated that it's associated with problems in the part of an infant's brain that controls breathing and waking. BChE is an enzyme of the cholinergic system, part of the autonomic system, which controls functions like blood pressure and breathing. The study authors say more research is needed to determine whether BChE tests might be able to identify and prevent future SIDS cases.

Smoking during pregnancy is one of the risk factors for SIDS, along with things like family history and premature birth. The researchers noted that animal studies have shown a tie between secondhand smoke and lower BChE. However, many other changes in the first six months of life are also likely to affect these enzymes and the nervous system in general.

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Coronavirus: As BA.2 subvariant of Omicron rises, lab studies point ...

(CNN) The BA.2 virus -- a subvariant of the Omicron coronavirus variant -- isn't just spreading faster than its distant cousin, it may also cause more severe disease and appears capable of thwarting some of the key weapons we have against Covid-19, new research suggests.

New lab experiments from Japan show that BA.2 may have features that make it as capable of causing serious illness as older variants of Covid-19, including Delta.

And like Omicron, it appears to largely escape the immunity created by vaccines. A booster shot restores protection, making illness after infection about 74% less likely.

BA.2 is also resistant to some treatments, including sotrovimab, the monoclonal antibody that's currently being used against Omicron.

The findings were posted Wednesday as a preprint study on the bioRxiv server, before peer review. Normally, before a study is published in medical journal, it is scrutinized by independent experts. Preprints allow research to be shared more quickly, but they are posted before that additional layer of review.

"It might be, from a human's perspective, a worse virus than BA.1 and might be able to transmit better and cause worse disease," says Dr. Daniel Rhoads, section head of microbiology at the Cleveland Clinic in Ohio. Rhoads reviewed the study but was not involved in the research.

The US Centers for Disease Control and Prevention is keeping close watch on BA.2, said its director, Dr. Rochelle Walensky.

"There is no evidence that the BA.2 lineage is more severe than the BA.1 lineage. CDC continues to monitor variants that are circulating both domestically and internationally," she said Friday. "We will continue to monitor emerging data on disease severity in humans and findings from papers like this conducted in laboratory settings."

BA.2 is highly mutated compared with the original Covid-causing virus that emerged in Wuhan, China. It also has dozens of gene changes that are different from the original Omicron strain, making it as distinct from the most recent pandemic virus as the Alpha, Beta, Gamma and Delta variants were from each other.

Kei Sato, a researcher at the University of Tokyo who conducted the study, argues that these findings prove that BA.2 should not be considered a type of Omicron and that it needs to be more closely monitored.

"As you may know, BA.2 is called 'stealth Omicron,' " Sato told CNN. That's because it doesn't show up on PCR tests as an S-gene target failure, the way Omicron does. Labs therefore have to take an extra step and sequence the virus to find this variant.

"Establishing a method to detect BA.2 specifically would be the first thing" many countries need to do, he says.

"It looks like we might be looking at a new Greek letter here," agreed Deborah Fuller, a virologist at the University of Washington School of Medicine, who reviewed the study but was not part of the research.

Mixed real-world data on subvariant's severity

BA.2 has been estimated to be about 30% more contagious than Omicron, according to the World Health Organization. It has been detected in 74 countries and 47 US states.

The US Centers for Disease Control and Prevention estimates that about 4% of Americans with Covid-19 now have infections caused by BA.2, but many other parts of the world have more experience with this variant. It has become dominant in at least 10 other countries: Bangladesh, Brunei, China, Denmark, Guam, India, Montenegro, Nepal, Pakistan and the Philippines, according to World Health Organization's weekly epidemiological report.

However, there's mixed evidence on the severity of BA.2 in the real world. Hospitalizations continue to decline in countries where BA.2 has gained a foothold, like South Africa and the UK. But in Denmark, where BA.2 has become the leading cause of infections, hospitalizations and deaths are rising, according to WHO.

Resistant to monoclonal antibody treatments

The new study found that BA.2 can copy itself in cells more quickly than BA.1, the original version of Omicron. It's also more adept at causing cells to stick together. This allows the virus to create larger clumps of cells, called syncytia, than BA.1. That's concerning because these clumps then become factories for churning out more copies of the virus. Delta was also good at creating syncytia, which is thought to be one reason it was so destructive to the lungs.

When the researchers infected hamsters with BA.2 and BA.1, the animals infected with BA.2 got sicker and had worse lung function. In tissues samples, the lungs of BA.2-infected hamsters had more damage than those infected by BA.1.

Similar to the original Omicron, BA.2 was capable of breaking through antibodies in the blood of people who'd been vaccinated against Covid-19. It was also resistant to the antibodies of people who'd been infected with Covid-19 early in the pandemic, including Alpha and Delta. And BA.2 was almost completely resistant to some monoclonal antibody treatments.

But there was a bright spot: Antibodies in the blood of people who'd recently had Omicron also seemed to have some protection against BA.2, especially if they'd also been vaccinated.

And that raises an important point, Fuller says. Even though BA.2 seems more contagious and pathogenic than Omicron, it may not wind up causing a more devastating wave of Covid-19 infections.

"One of the caveats that we have to think about as we get new variants that might seem more dangerous is the fact that there's two sides to the story," Fuller says.

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The virus matters, she says, but as its would-be hosts, so do we.

"Our immune system is evolving as well. And so that's pushing back on things," she said.

Right now, she says, we're in a race against the virus, and the key question is, who's in the lead?

"What we will ultimately want is to have the host be ahead of the virus. In other words, our immunity, be a step ahead of the next variant that comes out, and I don't know that we're quite there yet," she said.

For that reason, Fuller says, she feels like it's not quite time for communities to lift mask mandates.

"Before this thing came out, we were about 10 feet away from the finish line," she said. "Taking off the masks now is not a good idea. It's just going to extend it. Let's get to the finish line."

US officials fear the worst is yet to come for Kyiv - CNNPolitics

(CNN) Ukrainian forces have so far managed to stave off Russian ground forces massed less than 20 miles north of the embattled capital Kyiv -- but though they've defied US intelligence predictions that the city would likely fall within one to four days of a full-scale Russian assault, US officials warn that Russian President Vladimir Putin could imminently increase the intensity of the attack.

Stiffer than expected Ukrainian resistance and Russia's own logistical missteps have bogged down Russia's advance, US and western officials say, sparking a fragile optimism. The US has also continued sharing downgraded intelligence with the Ukrainians, including about Russian military moves, in an attempt to help Ukraine on the battlefield, two of the sources told CNN.

But intelligence and defense officials closely tracking the Russian campaign say that Putin still holds a number of moves in reserve that could devastate the Ukrainian resistance.

"From a purely military/tactical standpoint, Russia has the manpower and firepower to take Kyiv. No question," said an American source familiar with the intelligence. "And no matter how much resistance the Ukrainians put up."

Roughly a quarter of Russia's amassed troops have yet to enter Ukraine, a senior defense official told reporters on Monday -- a potential "second wave," according to two sources familiar with the intelligence -- and defense officials say Putin could yet order a far less restrained bombing campaign, including airstrikes, long-range missiles and artillery.

"They have been slowed and they have been frustrated by their lack of progress on Kyiv, and one of the things that could result is a reevaluation of their tactics and the potential for them to be more aggressive and more overt in both the size and the scale of their targeting of Kyiv," a senior defense official told reporters on Monday.

Administration officials warned lawmakers in classified briefings Monday that a "second wave" of Russian troops will likely consolidate the country's positions within Ukraine and by sheer numbers be able to overcome the Ukrainian resistance, according to two people familiar with the briefings.

"That part was disheartening," one lawmaker told CNN.

The officials also said Russia was likely going to lay siege to Kyiv and predicted ugly scenes of urban warfare, one of the people familiar with the matter said.

And at the end of the day, officials tracking the campaign say, the ugly truth remains that Ukraine is massively outgunned and outmanned -- even as Russia has made what military strategists say are a number of obvious blunders.

Already, Russia appears to be ramping up its campaign in the east and the south. In the northeastern city of Kharkiv, Russian forces have launched rocket attacks on at least one residential neighborhood that have killed civilians, according to Ukrainian officials and multiple social media videos geolocated by CNN. Meanwhile, in the small southern city of Mykolaiv, located on an inlet that would be a useful access point for Russians to bring in troops and supplies, the fighting has been among the most intense in Ukraine in recent days.

Concerns about Putin's state of mind

Perhaps most ominously, western officials are also warily watching Putin, under pressure from crushing economic penalties that have tanked the ruble and caused the Russian stock market to close. They fear those sanctions, combined with the lack of progress in Kyiv, may cause the unpredictable Russian leader to lash out even more.

JUST WATCHED French presidential sources: Putin struck Macron 'different' at recent meeting Replay More Videos ... MUST WATCH French presidential sources: Putin struck Macron 'different' at recent meeting 03:51

Senior US lawmakers familiar with the intelligence, western officials and former senior US officials with deep experience in Russia have begun to openly raise questions about the Russian leader's mental stability.

"Putin has been completely isolated, partly because of Covid," said the American source familiar with the intelligence. "He's now basically just by himself, completely cut off from most of his advisers, isolated geographically ... the only people talking to him are sycophants who are just feeding his resentment." The source added that the intelligence suggested Putin has not even been listening to his oligarchs -- traditionally the people who have had a key influence on his decision making.

Questions about Putin's mental state arose during the classified briefings to lawmakers, but they were not clearly answered by the administration officials, the sources familiar with the briefings said.

Republican Sen. Chuck Grassley of Iowa, who attended the Senate briefing, confirmed that Putin's mental state came up, but he declined to elaborate on what had been shared. He said, however, that regardless of the briefing, he personally is worried about Putin's mental state.

Sen. Marco Rubio of Florida, the top Republican on the Senate Intelligence Committee, tweeted Friday that "it's pretty obvious to many that something is off with #Putin," hinting that his assessment was based on intelligence briefings. "He has always been a killer, but his problem now is different & significant. It would be a mistake to assume this Putin would react the same way he would have 5 years ago."

On Sunday, Putin ordered Russia's nuclear forces into "special combat readiness," a heightened alert status that the Biden administration has characterized as part of a pattern of unprovoked escalation and "manufactured threats."

Holding back?

Five days into its multipronged assault on Ukraine, Russia has suffered repeated logistical failures that defense officials and independent military analysts say are largely of its own making. Russian mechanized forces that have been the tip of the spear have often outpaced their own sustainment units carrying fuel and other supplies, leaving the support units open to ambush and stranding forward-advancing forces without fuel in the tank.

"Whether they outran [sustainment capabilities] or whether they just didn't plan properly for it, or whether they just simply didn't execute their plan for it, I don't know," said the senior defense official. But, "on day 4, they're running out of gas and they've having logistics problems. Our assessment was that they did not believe they would be having those kinds of problems that early on."

Meanwhile, western officials have cheered on a better-than-anticipated showing by Ukrainian forces, in particular how effective they have been using western-provided Stinger shoulder-fired missiles and anti-aircraft artillery to take down an unknown number of Russian helicopters and fixed-wing aircraft.

"The Russians don't have complete control of the airspace of the entire country," said the senior western intelligence official. "In the areas in which the Russian military operations are the most intense on the ground, those are the areas where the Russians have the most control over the airspace in terms of air to air."

But Western officials still aren't entirely sure why Russia has held back some forces outside of Ukraine's borders, or why Russia has not yet carried out the kind of electronic warfare against Ukraine the west had been anticipating -- like massive hacking campaigns and attacks on critical infrastructure.

One official said the US believes Russia has been holding back on severing communications on the ground -- a tactic the west had expected early but has yet to happen -- because the Russian military forces need that infrastructure to communicate amongst themselves.

As for the troops left on the border, it's possible that Russia has planned the attack in waves in an effort to exhaust the Ukrainians with the first wave and then demolish them with a second wave of fresh troops, according to two sources familiar with the intelligence. It's also possible, according to one of those sources, that Russia has simply moved cautiously after facing a tougher fight than expected.

At this point, officials said, it's impossible to put a timeline on how long Ukrainian forces will be able to hold the Russians at the gates of Kyiv.

"I can't put a number [on how long Kyiv lasts]," the senior western intelligence official said. "I can't tell you it's going to be hours or days.

"While the Ukrainians are putting on a stiff defense, and a much better one than I think the Russians anticipated, there will be a time where they will run out of ammunition. There will come a time where they run out of fuel and they can't move," this person said. "We are mindful of that and they are mindful of that."

This story has been updated with additional reporting Monday.

Katie Bo Lillis
Natasha Bertrand
Barbara Starr

An 'awful' month of Covid-19 lies ahead, doctor says, but ...

What we can learn from the WHO Covid mortality numbers

This is why you should still have confidence in the FDA for vaccines

Johnson & Johnson's Janssen Covid-19 vaccine awaits administration at a vaccination clinic in Los Angeles, California on December 15, 2021. (Photo by Frederic J. BROWN / AFP) (Photo by FREDERIC J. BROWN/AFP via Getty Images)

FILE - In this photo provided by the North Korean government, North Korean leader Kim Jong Un, center, visits a pharmacy in Pyongyang, North Korea on May 15, 2022. Independent journalists were not given access to cover the event depicted in this image distributed by the North Korean government. The content of this image is as provided and cannot be independently verified. Korean language watermark on image as provided by source reads: "KCNA" which is the abbreviation for Korean Central News Agency. (Korean Central News Agency/Korea News Service via AP, File)

British singer Mick Jagger (C), US drummer Steve Jordan (back), guitar players Keith Richards (R) and Ronnie Wood (L) perform during the Rolling Stones "No Filter" 2021 North American tour at The Dome at America's Center stadium on September 26, 2021 in St. Louis, Missouri. (Photo by Kamil Krzaczynski / AFP) (Photo by KAMIL KRZACZYNSKI/AFP via Getty Images)

'Are you gonna let me answer a question?': Fauci and Paul face off in tense exchange

CNN —

While the highly transmissible Omicron variant continues to drive up Covid-19 cases and hospitalizations – and the numbers are likely to get worse before they get better – health experts say it’s critical Americans continue safe practices to prevent infections.

“I don’t buy the idea that we are all going to get Omicron and, therefore, just give up trying. I think that’s wrong,” Dr. Robert Wachter, chairman of the Department of Medicine at the University of California, San Francisco, told CNN’s Erin Burnett on Wednesday.

It’s likely that “the next month is going to be awful,” he said. But this does not mean that everyone should assume they will catch the virus, he said, noting the pattern of Omicron infections in the UK and South Africa.

“In a month or six weeks or eight weeks – hard to know – if we follow the pattern that South Africa has followed, if we follow what London appears to be showing us, they are starting to come down in cases,” Wachter said.

An ensemble forecast from the US Centers for Disease Control and Prevention published Wednesday predicts that more than 84,000 people could die of Covid-19 over the next four weeks, and cautions “current forecasts may not fully account for the emergence and rapid spread of the Omicron variant or changes in reporting during the holidays.”

The forecast could mean an average of 3,526 Covid-19 deaths per day, up from a current average of 1,251 each day, based on data from Johns Hopkins University.

To date, Covid-19 has killed at least 832,148 people and infected about 57.8 million in the US, according to JHU’s database.

Health care facilities are scrambling to handle staff shortages as hospitalizations for Covid-19 are increasing for both adults and children.

In the Kansas City metro area, hospitals are postponing certain surgeries due to employees out sick with Covid-19, according to more than a dozen doctors at a news conference Wednesday.

“This is, hands down, the toughest surge the medical community has had to face since the pandemic began in 2020,” according to Dr. Steven Stites, chief medical officer at The University of Kansas Health System.

Kansas Gov. Laura Kelly signed a state of disaster emergency on Thursday to alleviate some of the healthcare staffing shortages and constraints caused by the surge.

Frontline workers across other industries, such as education, retail and food services, are also facing an increased risk of exposure, with employees infected with Covid-19 needing time to recuperate.

In Massachusetts, senior administrators of Boston Public Schools stepped into classrooms Wednesday to help fill in for hundreds of teachers who have called out.

“Some of our schools are experiencing more than a quarter of staff absent because of positive Covid tests or other issues,” Boston Mayor Michelle Wu said.

In Chicago, about 340,000 students will miss a second day of school Thursday due to a showdown between the administration and the teachers’ union over in-person learning.

The best way to keep workplaces safe is to encourage mask-wearing and vaccinations, said Arthur Caplan, director of medical ethics at NYU Grossman School of Medicine.

The safety of others is also critical and well-documented in our society, Caplan told CNN’s Anderson Cooper on Wednesday

“We have restricted second-hand smoking, if you will, in public spaces due to second-hand smoke,” he said. “You can lose your ability to drive if you engage in risky behavior. So, we don’t live in a society that just says, ‘freedom means I can do what I want’ or ‘freedom means I have choice without any accountability or responsibility.’ When you hurt others, our mothers, put others at risk, you have got to take some responsibility.”

A health care worker at UMass Memorial Medical Center tends to a Covid-19 ICU patient in Worcester, Massachusetts. Erin Clark/The Boston Globe/Getty Images

Boosters approved for those as young as 12

Access to boosters has been expanded to more children, as the CDC updated its recommendations Wednesday for the Pfizer/BioNTech Covid-19 vaccine booster to include children as young as 12, at least five months after they finish the primary vaccine series.

The decision follows the US Food and Drug Administration’s earlier expansion of the emergency use authorization for the booster.

“It is critical that we protect our children and teens from COVID-19 infection and the complications of severe disease,” CDC director Dr. Rochelle Walensky said in a statement.

More than 72 million people are fully vaccinated and boosted against Covid-19, per CDC data. That’s less than half of the nearly 180 million people who are eligible to receive their booster shot and about a fifth of the total US population.

At least 67.5 million people ages 5 and up have not received their first dose of the vaccine, according to the latest CDC data.

No vaccine is currently authorized in the US for children under 5, but ongoing studies may produce data for analysis in the first half of 2022, NIAID director Dr. Anthony Fauci said Wednesday.

CDC will hold an independent briefing

The CDC will also hold a telebriefing on Friday to give updates on the pandemic. Walensky is scheduled to speak during that briefing.

It’s been months since the CDC has held a briefing like this. The agency usually participates in joint briefings with officials from the White House or the National Institutes of Health, such as Fauci. Its last independent Covid-19 briefing was July 27, 2021.

But the CDC has faced renewed criticism in recent weeks over confusion surrounding its guidelines on testing and isolation for people who test positive for Covid-19.

In late December it shortened the recommended times that people should isolate when they’ve tested positive for the virus from 10 days to five days if they don’t have symptoms – and if they wear a mask around others for at least five more days.

This week the agency updated that guidance after criticism from outside medical experts, and said that if people have access to a Covid-19 test and want to take it, the best approach is to use a rapid test toward the end of their five-day isolation period.

Expert: If you have symptoms, assume you have Covid

A new preprint study involving a small group of patients published Wednesday found it may take several days for people infected with the Omicron variant to test positive for Covid-19 with a rapid antigen test after also testing positive with a PCR test, raising concerns about the reliability of rapid tests to detect Omicron Covid-19 cases when the infections are still early.

Researchers found on the day of and the day immediately following a positive PCR result, rapid antigen tests were all negative, even though 28 of the 30 people in the study had enough virus in their body to transmit it to others.

On average, the time from a first positive PCR test to a first positive rapid antigen test was 3 days, the study found.

“The policy implication is that rapid antigen tests may not be as fit-for-purpose in routine workplace screening to prevent asymptomatic spread of Omicron, compared to prior variants, given the shorter time from exposure to infectiousness and lower infectious doses sufficient for transmission,” the authors wrote. The results are considered preliminary and have yet to be peer-reviewed.

Individuals who are experiencing Covid-19 symptoms should act as if they’re positive, epidemiologist Dr. Michael Mina said Thursday.

“The important thing is, when you feel symptoms, assume you’re positive at this point, especially with Omicron being so prevalent,” Mina said in an interview with eMed, where he is chief science officer. “Assume you’re positive, assume you’re infectious, and wait a day or two before taking that test, because it might be a day before the test turns positive. It might be two days.”

For individuals with access to rapid tests, the FDA stated that tests should be used as authorized after several health experts on social media suggested rapid tests may be more accurate if the throat is swabbed rather than nasal passages.

“The FDA has noted safety concerns regarding self-collection of throat swabs, as they are more complicated than nasal swabs – and if used incorrectly, can cause harm to the patient,” an FDA spokesperson said in a statement Wednesday. “The CDC recommends that throat swabs be collected by a trained healthcare provider.”

'Reassuring' data suggests Johnson & Johnson vaccine may still ...

(CNN) The US public and even some health experts may have underestimated the Covid-19 vaccine made by Janssen, a division of Johnson & Johnson, new data shows. And there's emerging evidence that it could still play an important role ahead.

A study published Thursday in the medical journal JAMA Network Open found that the J&J vaccine remains durable and effective, even through the surge of cases caused by the Delta variant. It was 76% effective overall in preventing Covid-19 infections and 81% effective in preventing Covid-related hospitalizations. The study also showed that it provided lasting immunity at least six months after the shots.

And a CNN analysis of information collected by the US Centers for Disease Control and Prevention showed the J&J vaccine had the lowest breakthrough infection rate of all the vaccines since the week ending December 25, the latest five weeks of available data.

In January, during the Omicron surge, breakthrough infections were highest among those who received the Pfizer/BioNTech vaccine, followed by those who got Moderna. Those vaccinated with the Johnson & Johnson shot had the lowest incidence of breakthrough infections.

As of the week ending January 22, there were 650 infections per 100,000 people with the J&J vaccine. With Moderna, there were 757 per 100,000, and with Pfizer, the rate was 862 per 100,000.

Unvaccinated people were particularly vulnerable to getting sick during the Omicron and Delta surges, just as they were with the original version of the coronavirus. They were 3.2 times as likely to get sick as people who had the J&J vaccine. The unvaccinated were 2.8 times as likely to become infected than those who got Moderna and 2.4 times as likely as those who got Pfizer.

"What we saw in the summertime and the fall during the Delta surge is that all three vaccines protected very, very well. But breakthrough rates in August, September of last year with the Janssen vaccine were slightly higher than Pfizer, and Moderna was slightly lower. But those differences were relatively small," said Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston. He helped to develop and study the J&J vaccine.

"But what we saw over time is that those differences then narrowed," he said. "And by the first week of December, what we saw in the data is that the lines cross," with incidence rates for the J&J/Janssen vaccine becoming lower than the others.

'Reassuring' data for J&J recipients

In March 2021, the J&J vaccine was the third to be authorized by the US Food and Drug Administration, and the initial response was more muted than the milestone authorizations of the mRNA vaccines from Pfizer/BioNTech and Moderna.

The vaccines work differently. The mRNA vaccines deliver blueprints, essentially, that train your body trains to fight that particular infection and any similar infection down the road. Adenovirus-vector vaccines, like J&J's, use a virus that can act like a Trojan horse. But instead of soldiers jumping out, the adenovirus releases genes that encode the coronavirus' spike protein.

The J&J vaccine stood out for other reasons, too: It came as a convenient single dose and didn't require special refrigeration, whereas the mRNA vaccines required two doses, and Pfizer's needed special cold storage. The flexibility was appealing for people who were afraid of shots or didn't have the time to get two shots. It was also better for countries without a solid health care infrastructure.

But its performance tempered some of the enthusiasm around it, especially from the public.

Whereas the mRNA vaccines were hailed for "astonishing" efficacy of more than 90%, the news that J&J was 65% effective at preventing symptomatic Covid-19 among clinical trial volunteers underwhelmed some.

From the start, the J&J vaccine supply was more limited. After after the vaccine was authorized, the federal government briefly paused its use due to safety concerns around rare blood clotting events. Even once vaccinations resumed, the pace of J&J vaccinations never recovered.

In December, the CDC changed its recommendations to say shots made by Moderna and Pfizer/BioNTech are preferred over J&J's. It also urges people who got the J&J shot to get a booster of one of the mRNA vaccines two months later.

The protection that the Covid-19 vaccines offered has waned over time, and none of them works as well against the variants that have popped up since the original coronavirus surfaced. But the science is starting to show that people who got the J&J Covid-19 vaccine may have some advantage.

Barouch told CNN that he "wasn't surprised at all" to see that the durability of the Johnson & Johnson vaccine appears to be last longer than that of the mRNA vaccines -- Pfizer/BioNTech and Moderna -- based on the incidence of breakthrough infections.

The mRNA vaccine technology has been shown to quickly elicit a potent and robust immune response after vaccination, but that can wane over time. Johnson & Johnson's virus-vector platform may not spark as powerful of an immune response in the short term, but it is known to have strong durability.

"Over time, the efficacy of the Pfizer and Moderna vaccines goes down, the efficacy of the J&J vaccines remains stable, and so it is exactly as you would predict: that they will converge and they will then cross," Barouch said.

The J&J vaccine also might have "a particular edge," he said.

"The immune system is actually made of two arms: the antibodies side and the T cells. And the type of T cells that are critical for prevention of serious illness are called CD8 T cells," Barouch said. "The J&J vaccine raises better CD8 T cells than the Pfizer and other mRNA vaccines, so the J&J vaccine might have a particular edge for variants like Omicron that largely escaped from antibody responses."

Overall, Barouch called this data "very reassuring" for recipients of the J&J vaccine.

"They should be reassured that they received a vaccine that gives very good protection for a long period of time," Barouch said. "And I think the second message is that I think people should learn about these new data in terms of considering booster shots, as well."

Prospects as a booster?

David Montefiori, a virologist at Duke University Medical Center, said "the J&J vaccine has kind of gotten a bad rap because of the efficacy, but the stability of the response is intriguing."

The antibody level went down with every vaccine during the Omicron surge, and that could mean people need an additional booster. More research is needed to find out.

A yet-unpublished study by the National Institutes of Health looking at a mix-and-match vaccine strategy saw good results when J&J was included, Montefiori said.

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"In people who got the Pfizer vaccine initially and then a boosted with the J&J vaccine, those people made pretty high levels of neutralizing antibodies to Omicron: 10 times higher than people who got two shots with just the J&J vaccine," he said. "So the J&J vaccine might be a good booster for people who got an mRNA vaccine initially."

The Johnson & Johnson vaccine can be used for primary doses or as a booster, but the CDC says the Pfizer and Moderna vaccines are recommended in most situations because of the risk of serious adverse events with the Johnson & Johnson vaccine.

The J&J vaccine has been linked to rare cases of blood clots with low platelets, known as thrombosis with thrombocytopenia syndrome or TTS. "It occurs at a rate of about 3.83 cases per million Janssen doses and has resulted in deaths," the CDC says.

Dr. Angela Branche , an infectious disease specialist and associate professor of medicine at the University of Rochester, said the side effect profile of the J&J vaccine "remains something that's of concern for some groups where that risk is high." Women ages 30 to 49 years are at increased risk of this rare adverse event, the CDC says.

But if that research pans out, the J&J vaccine may be useful as a booster for only certain populations.

"For some groups where that risk of developing serious blood clots is not very high, like older adults, this may be a good strategy," Branche said.

Montefiori said the vaccine deserves more study.

"I think there might still be a place for the J&J vaccine in the long-term picture of this pandemic," Montefiori said.

US Coronavirus: Americans may be faced with a different reality in ...

(CNN) The US is ringing in the new year amid a Covid-19 surge experts warn is exploding at unprecedented speed and could alter daily life for many Americans during the first month of 2022.

"Omicron is truly everywhere," Dr. Megan Ranney, a professor of emergency medicine at Brown University's School of Public Health, told CNN on Friday night. "What I am so worried about over the next month or so is that our economy is going to shut down, not because of policies from the federal government or from the state governments, but rather because so many of us are ill."

The nation broke records at least four times this week for its seven-day average of new daily Covid-19 cases, reporting an all-time high of more than 386,000 new daily infections Friday, according to the latest data from Johns Hopkins University. The high case count is already causing disruptions in the country.

In New York City, the Metropolitan Transportation Authority (MTA) is plagued with staffing issues and announced three subway lines -- the B, Z and W -- which service various parts of the boroughs, have been suspended.

"Like everyone in New York, we've been affected by the COVID surge. We're running as much train service as we can with the operators we have available," the MTA wrote on Twitter Thursday.

New York continues to break its own record, adding 85,476 reported Covid-19 cases, according to Saturday's briefing from New York Gov. Kathy Hochul.

Hospitalizations jumped to 8,451, up from around 8,000 in the report released Friday, according to the latest data. The state's seven-day positivity rate is 19.79%.

The number of one day case additions has increased 219% since Monday, when the state reported an addition of 26,737 cases.

Healthcare services -- exhausted after several surges of the virus and now stretched thin again by a growing number of Covid-19 patients -- are also already feeling impacts. The University of Maryland Capital Region Health this week joined a growing list of medical centers in the state to activate emergency protocols after a sharp rise in cases fueled staffing shortages and overwhelmed emergency departments.

"The current demand for care is depleting our available resources, including staffing," UM Capital Region Health said in a statement on Friday.

In Ohio, Gov. Mike DeWine on Wednesday announced the deployment of about 1,250 National Guard members as hospitals struggle with staffing shortages.

On the same day, the mayor of Cincinnati declared a state of emergency due to staffing shortages in the city's fire department following a rise in Covid-19 infections. The mayor's declaration said if the staffing problem goes unaddressed, it would "substantially undermine" first responders' readiness levels.

"Get ready. We have to remember, in the next few weeks, there's going to be an unprecedented number of social disruptions," Dr. Peter Hotez, dean of Baylor University's National School of Tropical Medicine, told CNN.

Those include flight disruptions as well, he said, because of TSA agent and air crew absences.

Thousands of flights have already been canceled or delayed throughout the holiday season as staff and crew called out sick. On Friday, the Federal Aviation Administration said an "increased number" of its employees were testing positive for the virus, and "to maintain safety, traffic volume at some facilities could be reduced, which might result in delays during busy periods."

Previous rules of virus are 'out the window'

The virus is now "extraordinarily contagious" and previous mitigation measures that used to help now may not be as helpful, CNN medical analyst Dr. Jonathan Reiner told CNN on Friday.

"At the beginning of this pandemic... we all were taught, you have a significant exposure if you're within six feet of somebody and you're in contact with them for more than 15 minutes. All these rules are out the window," Reiner said. "This is a hyper-contagious virus."

Now, even a quick, transient encounter can lead to an infection, Reiner added, including if someone's mask is loose, or a person quickly pulls their mask down, or an individual enters an elevator in which someone else has just coughed.

"This is how you can contract this virus," Reiner said.

The variant's transmissibility helps explain the staggering number of infections reported globally, including in the US. in the past week, several states have reported new case and hospitalization highs, shattering previous records.

New Jersey recorded more than 28,000 new Covid-19 cases through PCR testing, Gov. Phil Murphy wrote on Twitter Friday. In a news conference, the governor said the number was roughly "quadruple from just two weeks ago, and four times as many cases than during the height of last winter's surge."

"Our hospitals right now are at roughly the same numbers they were on the worst day of last winter's surge," he added. "The problem is that right now we don't see any sign of let up."

Other states, including Arkansas, Maryland and New York, also reported new records for case numbers.

And a sharp rise in infections -- especially in children -- could soon lead to a spike in hospital admissions, infectious diseases expert Dr. Jeanne Marrazzo said.

"The explosive rise in cases is really fueling what normally might be a relatively small proportion ... of kids who are experiencing these severe outcomes," she told CNN's Amara Walker on Friday. "But you put the gigantic numbers of cases together with the small number affected, plus the proportion of unvaccinated, and I'm really worried that we're going to be in for a tidal wave of admissions, particularly for kids in the coming weeks."

Child Covid-19 hospital admissions already reached an all-time high this week , with a record average of 378 children admitted to hospitals on any given day over the week ending December 28, according to the US Centers for Disease Control and Prevention and the US Department of Health and Human Services.

Children younger than 5 are not yet eligible for a Covid-19 vaccine, and a shot for those groups likely won't be available until mid-2022, experts say.

Concerns about returning to school

With the virus spreading, some staff members and experts are expressing concern about what school reopenings could mean.

"There will be pediatric hospitalizations," Hotez said. "And what's going to be the other tough piece in the next weeks, keeping the schools open, because of this high transmissibility -- especially if you start seeing absences of school teachers, bus drivers, cafeteria staff."

The Massachusetts Teachers Association, New England's largest public sector union, urged the state education commissioner this week to keep schools closed on Monday, except for staff Covid-19 testing.

"Using Monday as a day for testing and analyzing data will allow our school districts to make prudent decisions around staffing needs so they can continue in-person learning for students if it is safe or develop contingency plans if a district deems it to be necessary," Merrie Najimy, the association's president, said in a statement.

The state's Executive Office of Education said Friday schools will be open on Monday, despite the teacher union's request.

"The Department of Elementary and Secondary Education worked hard this week to make at-home rapid tests available to all public school teachers and staff in light of the testing shortages being experienced around the country. Massachusetts is one of only a handful of states supplying rapid tests to its teachers. It is a not a requirement for teachers to return to work, or necessary to reopen schools after the holiday break," Colleen Quinn, a spokesperson for the office, said in a statement.

"It is disappointing," the statement added, "that once again the MTA is trying to find a way to close schools, which we know is to the extreme detriment of our children."

Atlanta Public Schools (APS) announced all district schools will operate virtually through Friday, January 7, for all students and staff, according to a statement on Saturday.

Citing the surging Covid-19 cases, APS said the district elected to postpone in-person learning until Monday, January 10. The move will allow students and staff to be tested and if needed, to isolate and quarantine, per CDC and Department of Health Guidelines, according to APS.

All APS staff members are required to report to their workplaces on Monday for Covid-19 testing, the statement said.

Neighboring Fulton County Schools and DeKalb County Schools also announced Saturday they are starting online next week as students return to classes after the holiday break, according to verified tweets from both districts.

Fulton and DeKalb also aim to return to in-person instruction on January 10.

Meanwhile, a growing number of colleges and universities across the country are making changes to the beginning of the 2022 spring semester as a result of the case surge.

Duke University extended its plan for remote classes by another week because of an "incredibly high" positive case count among faculty and an increasing number of cases among students who are already in the area, the school said Friday.

Michigan State University announced Friday that classes will start primarily remotely on January 10 and will stay remote for at least three weeks.

"I realize that students prefer to be in person, and so do I," Samuel L. Stanley Jr., the university's president, said in a statement. "But it is important that we do so in a safe manner. Starting the semester remotely and de-densifying campus in the coming weeks can be a solution to slowing the spread of the virus."

Correction: A previous version of this article misstated the number of records broken this week in the seven-day average of new daily Covid-19 cases. The most recent average figure has also been updated to reflect the latest data from JHU.

New studies bring BA.2 variant into sharper focus - CNN

(CNN) On the heels of concerning new lab and animal experiments suggesting that BA.2 may be capable of causing more severe disease than the original Omicron strain, two new studies are helping to show how well human immunity is defending against this strain in the real world.

BA.2 is about 30% more transmissible than the original Omicron variant, BA.1, according to early studies from the UK and Denmark, and it is now causing about 1 in 5 Covid-19 cases worldwide, according to the World Health Organization.

Even as Covid-19 cases have been dropping around the world, the relative proportion of cases caused by BA.2 has been increasing. It is outcompeting the original Omicron strain in at least 43 countries , prompting fears of another devastating pandemic wave.

"As of now, I don't think that we need to sound a global alarm. But I do think that we need to pay attention to BA.2 because it does appear to have a growth advantage over BA.1," says Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston.

Like the BA.1 strain, BA.2 also has features that help it escape some immunity from vaccines and from most monoclonal antibody treatments, though recent boosters improve personal protection and antiviral pills are still expected to work against this subvariant.

Now new studies are providing some reassurance that while BA.2 may overtake its genetically distant cousin, it won't likely lead to greater numbers of hospitalizations and deaths.

"The situation that we're seeing on the ground, and I get this from talking to a number of my colleagues who actually do the genomic surveillance, is BA.2 is kind of creeping up in terms of numbers, but it's not the meteoric rise that we saw with BA.1," said Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan in Canada.

That's because in many countries like the US, UK, and Denmark, BA.2 has hit speed bumps left in its wake by BA.1, which was already very contagious.

"It's so soon after that initial BA.1 peak that you have a lot of people who were either vaccinated or boosted ... [or] got Omicron, and so right now all of those people will have relatively high titers of antibodies, neutralizing antibodies that will protect against infection," Rasmussen says.

The new studies are preprints, which means they were posted to an online library of medical research before being reviewed by outside experts and published in medical journals.

No increase in hospitalizations

The first new study comes from South Africa, where BA.2 grew rapidly, rising from 27% to 86% of new Covid-19 infections over the course of a single week in February. Researchers looked at cases tied to more than 95,000 positive Covid-19 tests. Among these, roughly equal proportions of people were hospitalized for their infections -- roughly 3.6% of people who had presumed BA.2 infections compared to 3.4% of those with signs infections caused by BA.1.

After researchers accounted for things that might influence a person's risk of severe disease, such as older age, they found no difference in the risk for hospitalization between people infected by BA.1 and those infected by BA.2. Roughly one-quarter of people hospitalized with both BA.1 and BA.2 infections were fully vaccinated.

Those findings echo hospitalization studies from Denmark, where BA.2 is also the predominant cause of Covid-19 infections.

The lead researcher on the South African study, Dr. Nicole Wolter, says that while it's difficult to say how the South African experience with this variant may translate to other countries, what they're seeing from BA.2 after their fourth wave isn't a second peak, but a longer tail.

"We have seen an extended wave which has currently plateaued at a higher level than we have seen in previous inter-wave periods," Wolter wrote in an email to CNN. "This may however also be influenced by schools opening following the December holiday period and a general relaxing of restrictions," wrote Wolter, who is a principal medical scientist at the National Institute for Communicable Diseases in Johannesburg.

Though cases have stayed at a high level, and most are now caused by BA.2, hospitalizations have continued to decline.

What about reinfection risk?

The second new study , from Denmark's Statens Serum Institut -- the country's equivalent to the US Centers for Disease Control and Prevention -- looked at the risk of reinfection with BA.2 after recovery from a Covid-19 infection caused by other recent variants, including Delta and BA.1.

The study found that people who've recently had a Covid-19 infection caused by Omicron or Delta can be reinfected by the emerging BA.2 subvariant, but such cases appear to be uncommon, afflict mostly those who are unvaccinated and result in mostly mild infections.

BA.2 is currently the dominant cause of Covid-19 in Denmark. It overtook BA.1 during the second week of January there.

To look at reinfection risk, researchers combed through more than 140,000 viral genomes that were sequenced from infections during the period when Omicron became dominant (late November to mid-February 2022) to find people who had a new positive test 20 to 60 days after a previous one.

They found a total of 263 reinfections, with 190 of those caused by the BA.2 variant. In 140 cases, the person was reinfected by BA.2 after an infection caused by the Delta variant. There were 47 cases where people were first infected by BA.1 (the original Omicron variant) followed by the BA.2 subvariant.

Researchers then did a more in-depth analysis of those 47 reinfections where BA.2 followed BA.1. Most of the individuals who were reinfected were young -- 30 were under age 20. None of the reinfected individuals was over age 40 and nearly all -- 42 of the 47 individuals -- were unvaccinated.

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For the most part, reinfections were mild; 28 people had no symptoms or mild symptoms. Five people experienced symptoms that were characterized as moderate, akin to flu-like symptoms. There were no hospitalizations or deaths reported among reinfected individuals.

The study shows that "reinfection can happen with people who recently recovered from BA;1, but it's pretty rare. And in all those cases, it wasn't severe," says Rasmussen, who reviewed the study but was not involved in the research.

What that means she says is that while BA.2 reinfection is a risk, it is a small risk relative to the entire population, and "that recent immune boost caused by either boosters, or recent Omicron infection is largely going to protect most of the population against it," she said.

Russia 'will move in' to Ukraine, Biden predicts, but 'minor incursion ...

(CNN) President Joe Biden on Wednesday predicted Russia "will move in" to Ukraine , citing existential concerns by the country's president, Vladimir Putin, even as he acknowledged disunity within NATO over how to respond to a "minor incursion."

The candid assessment laid bare the struggle Biden faces in creating meaningful consequences and deterrents for Moscow, which remains closely intertwined economically with the United States' top European partners.

The remark elicited near-immediate outcry in Kyiv, where officials have been meeting with Biden's top diplomat as Russian troops amass on the country's border . High-level attempts to clean-up the comment soon followed at the White House.

While Biden vowed withering economic consequences on Russia should Putin send his troops over the frontier, including restricting its financial transitions in US dollars, he suggested Western nations were not in sync on what to do should a lesser violation occur.

"It's one thing if it's a minor incursion and we end up having to fight about what to do and not do," Biden told reporters at an East Room news conference . "But if they actually do what they're capable of doing with the forces amassed on the border, it is going to be a disaster for Russia if they further invade Ukraine."

Later, asked to clarify what he meant by "minor incursion," Biden said he drew the line at "Russian forces crossing the border, killing Ukrainian fighters"

"I think that changes everything," the President said. "But it depends on what he does, to what extent we'll get total unity on the NATO front."

"It's very important that we keep everyone in NATO on the same page. That's what I'm spending a lot of time doing, and there are differences," he went on. "There are differences in NATO as to what countries are willing to do, depending on what happens."

The candid assessment of NATO's divisions -- which have been well documented, even as US and Western officials seek to project unity amid the crisis -- left Ukrainian officials aghast. One told CNN's Matthew Chance he was "shocked that the US President Biden would distinguish between incursion and invasion" and suggest that a minor incursion would not trigger sanctions.

"This gives the green light to Putin to enter Ukraine at his pleasure," the official added, claiming he'd never heard any nuance like this from the US administration before.

"Kyiv is stunned," he said, referring to the Ukrainian government.

The White House sought to explain Biden's remarks by pointing out a Russian attack in cyberspace or through paramilitary forces would prompt a reciprocal response compared to a scenario where Russian troops move from their positions into Ukraine

"President Biden has been clear with the Russian President: If any Russian military forces move across the Ukrainian border, that's a renewed invasion, and it will be met with a swift, severe, and united response from the United States and our Allies," press secretary Jen Psaki wrote in a statement following Biden's marathon news conference.

"President Biden also knows from long experience that the Russians have an extensive playbook of aggression short of military action, including cyberattacks and paramilitary tactics," Psaki went on. "And he affirmed today that those acts of Russian aggression will be met with a decisive, reciprocal, and united response."

A senior administration official said if Russian military forces tried to take Ukrainian territory by force and violated Ukrainian sovereignty -- whether that was a "small portion or a large portion" of land -- that would constitute an "invasion" by the Biden administration's standards and would warrant severe penalties.

And while the official acknowledged the US and NATO members likely will not have the "same list" of targets and details matching on every measure, the response would remain "highly unified" and "provide a force multiplier to actions we take."

Biden's remarks came as the US entered what officials have deemed a dangerous period, when a Russian invasion could occur at any moment. The President, while acknowledging lingering uncertainty over Putin's intentions, said Wednesday he believed the Russian leader would soon invade Ukraine.

"I'm not so sure he is certain what he is going to do. My guess is he will move in. He has to do something," Biden said, describing a leader searching for relevance in a post-Soviet world. "He is trying to find his place in the world between China and the west."

Biden's prediction of an invasion was the firmest acknowledgment to date the United States fully expects Putin to move after amassing 100,000 troops along the Ukraine border.

After speaking with Putin twice last month, Biden said he believed his Russian counterpart had a good understanding of the economic sanctions he was preparing to enact.

"He's never seen sanctions like the ones I promised will be imposed if he moves, number one," he said, adding the level of punishment would depend on what Russia's invasion looks like.

That includes limiting Russian transactions in US financial institutions -- "anything that involves dollar denominations," Biden said.

The President warned Russian lives would be lost in an invasion, along with potential Ukrainian casualties.

"The cost of going into Ukraine in terms of physical loss of life for the Russians -- they'll be able to prevail over time but it's going to be heavy," he said. "It's going to be real. It's going to be consequential. Putin has a stark choice. Either de-escalation or diplomacy. Confrontation and consequences."

"This is not all just a cake walk for Russia," he went on. "Militarily, they have overwhelming superiority. And as it relates to Ukraine, they'll pay a stiff price immediately, near term, medium term and long term if they do it."

Biden speculated Putin was not seeking "any full-blown war," but said he did believe he was looking for some type of confrontation: "Do I think he'll test the west? Test the United States and NATO as significantly as he can? Yes, I think he will. But I think he'll pay a serious and dear price for it."

Biden's prediction came after Ukrainian President Volodymyr Zelensky on Wednesday urged Ukrainians to not panic and to "calm down" over fears of a possible Russian invasion.

"All our citizens, especially the elderly, need to understand this: Everyone needs to exhale. Calm down. Don't run for emergency supplies like buckwheat and matches. To all the media: Remain as the media, not become a source of mass hysteria. Do not help the enemy in the pursuit of hype by reporting daily that war may happen tomorrow! This will definitely not stop it."

"What is new here? Is this not the reality for the past eight years? Didn't the invasion begin in 2014? Did the threat of the war emerge just now?" he said.

The only reason for "panic is that after eight years we are still influenced by this panic," he added.

Zelensky said Russia's "aim is to weaken Ukraine" in order to force Kyiv to concede to Moscow and "to create such a background that our 'no' sounds weaker."

The Ukrainian leader said Moscow is "actively attacking your nerves, not our state. So that you have a constant feeling of panic."

This story and its headline have been updated with additional reporting Wednesday.