As COVID-19 cases surge in China, infectious disease experts say the threat of a new variant is possible. The sooner the CDC knows about new variants, the faster it can respond. That is why the Biden Administration is ramping up a CDC Traveler Genomic Surveillance program that asks travelers from international flights to voluntarily do a nasal swab.

Dr. Cindy Friedman, with CDC Travelers' Health Branch, says the program currently targets approximately 500 flights per week from more than 30 countries.

"The program started back in September of 2021 with three airports at JFK, Newark and San Francisco," Dr. Friedman said. "Then, omicron came in November of 2021 and we added Atlanta. And then, the end of China's zero-COVID policy led to the expansion recently to a Seattle and LAX Los Angeles Airport."

Dr. Friedman says there are two parts to the program that are complementary to each other. One is getting nasal swabs from travelers who volunteer. The other is anonymously testing wastewater. When they get a positive result for COVID, the biological sample is sent to a lab to analyze what variant it is.

We've known for a while that SARS-CoV-2, the virus that causes COVID-19, can be found in wastewater. It serves as an early detection system to know what's circulating in a specific region or in other places across the globe.

Dr. Friedman says it's helpful when a new variant is detected because action can be taken immediately.

"It could be anything from, you know, we recommend wearing a mask because there is a new variant," Dr. Friedman said. "Or our lab will check the efficacy of the vaccine against a new variant, or the treatments, the antiviral drugs. I mean, it's really important to know that the medicines that you're recommending work against the newest version of the virus."

Dr. Friedman says the program successfully discovered the BA.2 and BA.3 subvariants during the early days of omicron. She says airports will likely be the first to know if a new variant comes along.

Ginkgo Bioworks is a partner of the program that does genomic sequencing along with XpresCheck.

"The idea of having airports as places to monitor for dangerous pathogens, this is like the dream of biosecurity infrastructure," Ginkgo Bioworks General Manager Matthew McKnight said. "And I think the realization that a lot of people have come to is that it isn't science fiction, it is entirely doable."

McKnight says he expects this technology to become a permanent part of national security.

"Certainly the vision like radar is that you should be looking for more and more different things, including in the future unexpected pathogens or as we move into a new and scary world, you know, thinking about being able to monitor for genetic engineering or any sort of biothreats that might be emerging in the national security space," McKnight said.

Dr. Friedman would like to thank international travelers who take a few minutes of their time to provide a nasal swab and she wants to reassure everyone the program is anonymous.

 

The CDC published new information Friday about the performance of COVID-19 booster shots.

In a new study, researchers found that after receiving a third dose of the vaccine, protection wanes over time.

When the omicron variant was dominant, effectiveness decreased as soon as four months after the third dose.

However, protection from serious illness was still high after the third dose.

In the study, effectiveness was higher among people who had received the booster shot, than among people who only received two doses of the vaccine.

Researchers also noted that effectiveness after a booster was higher when delta was the dominant strain.

Health experts expect protection from the vaccines to wane.

Previous evidence had already suggested that vaccines offered less protection against the omicron variant in comparison to earlier versions of the virus.

The CDC still recommends people to remain up to date with COVID-19 vaccinations to protect themselves against the virus.

Three large new studies from the U.S. Centers for Disease Control and Prevention highlight the importance of getting a booster shot to provide the best protection against the omicron coronavirus variant.

This is the first real-life data to examine the effect of boosters against omicron, which now accounts for more than 99% of coronavirus cases in the United States. The studies, released Friday, raise the question of whether people with just two vaccine doses should still be considered fully vaccinated.

"I think we have to redefine fully vaccinated as three doses," said Dr. William Schaffner, a longtime CDC vaccine adviser who was not involved with the studies.

The studies have an enormous scope, involving millions of cases, hundreds of thousands of visits to emergency departments and urgent care centers, and tens of thousands of hospitalizations among adults.

Getting boosted was 90% effective at preventing hospitalizations during a period in December and January when omicron was the dominant variant, according to a CDC study that looked at nearly 88,000 hospitalizations across 10 states.

In comparison, getting two shots was 57% effective when it had been at least six months past the second shot

Tracking the omicron surge

Getting boosted was 82% effective at preventing visits to emergency rooms and urgent care centers, according to the study, which looked at more than 200,000 visits in 10 states.

In comparison, getting two shots was only 38% effective at preventing those visits when it had been at least six months past the second shot.

"I think it's the third dose that really gives you the solid, the very best protection," Schaffner said.

That study was published Friday in the CDC's Morbidity and Mortality Weekly Report. A second study, also published in Friday's MMWR, concluded that people with three shots were less likely to get infected with omicron. Looking at data from 25 state and local health departments, the CDC researchers found that among those who were boosted, there were 149 cases per 100,000 people on average each week. For those who had only two doses, it was 255 cases per 100,000 people.

A third study, to be published in the medical journal JAMA, showed that having a booster helped prevent people from becoming ill with omicron. That study of just over 13,000 U.S. omicron cases found that the odds of developing a symptomatic infection were 66% lower for people who were boosted compared to those who had only received two shots.

All three studies found that unvaccinated people faced the highest risks of becoming sick with COVID-19.

The CDC currently says a person is considered fully vaccinated after they've received their primary COVID-19 vaccines — two weeks after receiving their second dose of an mRNA vaccine, or two weeks after their first dose of the Johnson & Johnson vaccine. Booster doses are recommended for everyone age 12 and older five months after their primary vaccination series.

Less than half of those eligible to receive booster shots have gotten one, and only about a quarter of the total U.S. population is fully vaccinated and boosted, according to CDC data.

Nearly 20% of the U.S. population eligible to be vaccinated — those age 5 and older — has not received any dose of COVID-19 vaccine.

Both vaccination and prior infection help protect against new COVID-19 infections, but vaccination protects against hospitalization significantly more than natural immunity from prior infection alone, according to a study published Wednesday by the U.S. Centers for Disease Control and Prevention.

Researchers analyzed the risk of COVID-19 infection and hospitalization among four groups of individuals: vaccinated with and without prior infection and unvaccinated with and without prior infection. The study case data from about 1.1 million cases in California and New York between the end of May and mid-November 2021. Hospitalization data was available from California only.

Overall, COVID-19 case and hospitalization rates were highest among unvaccinated people who did not have a previous diagnosis.

At first, those with a prior infection had higher case rates than those who were vaccinated with no history of prior infection. As the delta variant became predominant in the U.S. in later months, this shifted and people who survived a previous infection had lower case rates than those who were vaccinated alone, according to the study.

Tracking the omicron surge

"Experts first looked at previous infections confirmed with laboratory test by the spring of 2021, when the alpha variant was predominant across the country. Before the delta variant, COVID-19 vaccination resulted in better protection against a subsequent infection than surviving a previous infection. When looking at the summer and the fall of 2021, when delta became dominant in this country, however, surviving a previous infection now provided greater protection against subsequent infection than vaccination," Dr. Benjamin Silk, lead for CDC's surveillance and analytics on the Epi-Task Force, said on a call with media Wednesday.

However, this shift coincides with a time of waning vaccine immunity in many people. The study did not factor the time from vaccination — and potential waning immunity — into the analysis. The study also does not capture the effect booster doses may have and was conducted before the emergence of the omicron variant.

Throughout the period of the study, risk of COVID-19 hospitalization was significantly higher among unvaccinated people with no previous COVID-19 diagnosis than any other group.

"Together, the totality of the evidence suggests really that both vaccination and having survived COVID each provide protection against subsequent reinfection, infection and hospitalization," said Dr. Eli Rosenberg, New York State Deputy Director for Science. "Having COVID the first time carries with it significant risks, and becoming vaccinated and staying up-to-date with boosters really is the only safe choice for preventing COVID infection and severe disease."

Experts also noted that characteristics of variants change, including how well they affect immunity from prior infections.

The CDC said in a statement it will publish additional data on COVID-19 vaccines and boosters against the dominant omicron variant later this week.

Data from the Centers for Disease Control shows, as of Jan. 1, only about 40% of pregnant women have been vaccinated against COVID-19.

A new study out of Scotland is shining a much larger light on the benefits and safety of getting vaccinated while pregnant.  

More pregnant mothers are weighing whether to get the vaccine, especially with the surging omicron variant.

"I didn't want to get it and potentially harm my baby but looking back, that doesn't really make any sense because I obviously wouldn't have wanted to get COVID with the baby," Heaven Taylor-Wynn said. 

Doctors are trying to convince their pregnant patients to get the vaccine because they are seeing rough outcomes in some unvaccinated pregnant women and their babies. 

"I felt like there was a herd of elephants on my chest, and I couldn't breathe," Ashley Duque said.

"I've seen women they got really bad preeclampsia and a funny variant of preeclampsia called help syndrome that makes them very, very, very sick and requires urgent delivery," said Dr. Brad Holbrook, maternal fetal medicine specialist at Community Medical Center.

"I've seen women with stillbirths. I've seen babies die after they were born," she added.

The study out of Scotland confirms everything doctors like Holbrook have been saying,

The Scotland team studied all women who were pregnant or became pregnant from December 2020 through October 2021. 

"They looked at the entire population of the whole country and because they have a whole, you know, an integrated system," Dr. Holbrook said. "They have 130,000 women in this study that essentially showed the same things, which is that, that women who get COVID are potentially in for some problems. So women who get COVID are more likely to have a pre-term delivery, a stillbirth complication with baby or with their pregnancy, and that women who are vaccinated and then get sick with COVID are very likely to have a much more mild course, so it really just confirmed everything that we've seen."

Among unvaccinated women, the study found they made up 77.4% of COVID infections. They accounted for 90.9% of cases that required hospitalization or critical care, and all 450 fetal and newborn deaths associated with the virus. The rate of deaths in babies after 28 weeks was much higher in women who got COVID-19 within a month of giving birth.  

"The risk of getting infected is pretty high, and the risks involved in being vaccinated are almost nonexistent," said Dr. Alisa Kachikis, assistant professor of maternal fetal medicine at University of Washington.

"I do feel like when I can sit down and talk with them face-to-face about it, look, you know, I'm not representing a drug company," Dr. Holbook said. "I'm not representing the government. I'm just representing the science and what I've read and understand about this and my own experience and based on that and what I've seen, I've seen a lot of complications from COVID."

The highly-transmissible omicron variant brings new concerns, especially in places just starting to experience the surge, like Montana.

"We're gonna have this big bunch of pregnant women come in really sick with COVID and not just pregnant women, unpregnant people as well coming into the hospital, and the hospital is gonna be totally full and understaffed," Dr. Holbrook said. "It's gonna be a very difficult couple of weeks, I think."

This story was originally reported on Newsy.com.

WASHINGTON, D.C. — As the omicron variant sweeps across the nation, prompting long lines at COVID testing sites, there is a small silver lining: there are fewer hospitalizations and deaths from omicron than from last year's delta variant.

"Our vaccines, especially when combined with boosters, have remained extremely effective at keeping people out of the hospital and it is saving their lives," said U.S. Surgeon General Dr. Vivek Murthy.

Still, since omicron began spreading in the U.S. over the holiday season, there have been millions of new COVID infections.

“This omicron variant is more transmissible than previous versions,” said Dr. Bruce Y. Lee, a professor at the CUNY’s Graduate School of Public Health and Health Policy.

Dr. Lee is also the executive director of PHICOR (Public Health Informatics, Computational and Operations Research) and has been studying and tracking COVID since the pandemic began.

“Based on the data, it looks like the peak of this current omicron wave will probably occur sometime in mid-January,” he said.

By then, millions more Americans could potentially be infected with COVID. However, it’s what happens in the months after those infections that will need to be looked at closely, including what omicron might mean in terms of new long-haul COVID cases.

“Long COVID is something that's many times overlooked and not discussed,” Dr. Lee said. “People are focusing on things like deaths or potentially hospitalizations, and so many people tend to forget there is a significant percentage of people who are suffering from long COVID.”

Dr. Lee says with previous variants, there has been some correlation between how severe a COVID case is and how likely that person will become a long-hauler. Yet, he says, there is something about that which needs to be emphasized.

“This is not a super strong correlation,” he said. “Meaning, that there have been many cases of people having mild milder symptoms or milder COVID-19 early on, but they continue to have persistent symptoms.”

Those symptoms can run the gamut: from a loss of taste or smell to muscle pains to brain fog, among others.

The World Health Organization defines long COVID as having symptoms more than three months after initial infection, a timeline not reached with omicron yet.

“So, it's not clear what percentage of people who've been infected with the omicron variant will develop these persistent long COVID symptoms versus other variants,” Dr. Lee said.

It is something that, for omicron cases, might not become clearer until the spring.

WASHINGTON —

Federal health officials on Thursday pressed nursing home workers to get their booster shots amid a spike in COVID-19 cases among staffers and a concerning lag in booster vaccination for residents and staff.

The omicron variant "is lightning fast, and we can't afford another COVID-19 surge in nursing homes," Health and Human Services Secretary Xavier Becerra said in a livestreamed appeal to the industry. "You know that. I know that. Higher numbers of COVID cases would likely once again have a devastating impact on our loved ones ... and we know we just have to work doubly hard to keep them safe."

Nursing homes are a testing ground for President Joe Biden's assertion that the United States is much better prepared to handle a surging virus than it was last winter. Although residents are a tiny proportion of the population, they represent a disproportionate share of Americans who have died in the coronavirus pandemic. Earlier this year the advent of vaccines brought the virus under control in nursing homes and allowed them to reopen to visitors. But that return to normalcy could be in jeopardy as omicron pushes COVID-19 cases to new highs for the nation.

Cases among nursing home staffers jumped to 10,353 for the week ending Dec. 27, a rise of nearly 80% from the previous week, according to data from the Centers for Disease Control and Prevention. Staff deaths increased to 58, tripling from the previous week. Among residents, who are more heavily vaccinated, cases went up slightly and the data showed no increase in deaths.

With medical experts advising that a booster shot is critical to defend against omicron, Becerra said only 57% of nursing home residents and 25% of staff and have gotten boosters. That's clearly behind a booster rate of nearly 66% among people age 65 or older and about 45% for adults of all ages, according to statistics from the White House.

"We've got to change that," Becerra said.

The administration is urging some 1,400 federally funded community health centers across the land to partner with local nursing homes in a renewed vaccination campaign.

Nursing home workers were supposed to be fully vaccinated by Jan. 4 under an earlier order issued by the Centers for Medicare and Medicaid Services, which required staff at health care facilities that receive government money to get their shots. That directive got ensnared in litigation and the Supreme Court has set a special session next week to hear arguments on it, along with the much broader Biden administration vaccine mandate for workers at larger companies of all kinds. Together the orders would affect about 100 million employees.

"Once again nursing homes are really the ground zero," said Harvard health policy professor David Grabowski, who has tracked the impact of the pandemic on residents and staff. "How well we do in combating this virus can often be discerned by just looking at the nursing homes."

Grabowski said the Biden administration is right to raise the alarm now. "We see this time and time again: When staff (infection) rates go up, resident rates go up," he explained. Staffers unwittingly bring in the virus from surrounding communities, a common trigger for nursing home outbreaks.

Vaccines enabled nursing homes to weather the delta variant surge earlier this year, and timely booster shots should go a long way toward blocking omicron. "The more vaccines and boosters we have, the more lives we are going to save over the course of the winter," Grabowski said.

But some states are already seeing trouble.

COVID-19 outbreaks in Mississippi nursing homes have almost doubled in the past week, and officials say that indicates the state is probably heading into another major surge of virus cases and hospitalizations.

There were 63 outbreaks in Mississippi nursing homes Monday, about twice the number reported last week, state epidemiologist Dr. Paul Byers wrote in a midweek memo to Mississippi hospitals and health care providers.

Along with other data, that points to "very rapid growth of COVID-19 infection and transmission...we have now entered our 5th wave of COVID-19 in the state," Byers wrote.

One of the major nursing home industry groups is backing the administration's push on boosters.

The American Health Care Association said in a statement it's asking members to "double down on their efforts to get as many residents and staff fully vaccinated and boosted as soon as possible."

___

Associated Press writer Leah Willingham in Jackson, Mississippi, contributed to this report.

The U.S. hit a seven-day average of 265,427 new COVID-19 cases on Tuesday, blowing past the country's previous record of about 252,000 daily cases, reported nearly a year ago on Jan. 11.

The new peak, according to Johns Hopkins University data, comes amid a rapid acceleration of infections in the United States — and across the world — since last month.

And experts predict the omicron variant — the most contagious strain of coronavirus yet — is going to make the start of 2022 very difficult.

"January is going to be a really, really hard month. And people should just brace themselves for a month where lots of people are going to get infected," said Dr. Ashish Jha, dean of the Brown University School of Public Health.

And the U.S. could "see half a million cases a day — easy — sometime over the next week to 10 days," CNN medical analyst Dr. Jonathan Reiner said Sunday.

Most people who are vaccinated and boosted won't get severe illness, but that won't be true for the unvaccinated, Jha said.

"A lot of people who have not gotten a vaccine are going to end up getting pretty sick, and it's going to be pretty disruptive," Jha said. "My hope is as we get into February and certainly by the time we get into March, infection numbers will come way down, and it'll also start getting (into) spring, and the weather will start getting better. And that will also help."

Despite calls from experts for Americans to get their vaccines and boosters, the rate of booster doses getting administered has fallen in recent weeks — while only 32.7% of the country's fully vaccinated population is boosted.

In addition to getting vaccinated and boosted, people can protect themselves by taking precautions in public, Jha said.

"I would urge people to wear a higher quality mask any time they're in a place with lots of people and they're going to be indoors for any extended period of time," Jha said.

A surgical mask might be fine for a quick grocery store trip in an empty store, but for other events, a well-fitting N95 or KF94 mask provides better protection, he said.

Looking ahead to New Year's Eve on Friday, small gatherings of fully vaccinated people will be safe, Dr. Anthony Fauci said. But people should avoid large parties where they don't know the vaccination status of all guests, he said.

"When you are talking about a New Year's Eve party where you have 30, 40, 50 people celebrating, you do not know the status of the vaccination, I would recommend strongly: Stay away from that this year," said Fauci, the director of the National Institute of Allergy and Infectious Diseases. "There will be other years to do that. But not this year."

Pediatric hospitalizations nearing previous record

Holiday gatherings, like those over Christmas and New Year's, have some health care workers worried about the impact on children in the coming weeks -- especially those who are too young to be vaccinated.

"We've just had all of these kids mixing together with everybody else during Christmas," said Dr. Claudia Hoyen, the director of pediatric infection control at UH Rainbow Babies and Children's Hospital in Ohio.

"We have one more holiday to get through with New Year's, and then we'll be sending everybody back to school. Everybody is kind of waiting on the edge, wondering what we'll end up seeing."

Nationwide, pediatric COVID-19 hospitalizations are nearing the record high set in September.

On average, roughly 305 children were admitted to the hospital with COVID-19 on any given day over the week that ended Dec. 26, according to data from the Centers for Disease Control and Prevention and the US Department of Health and Human Services.

That's more than a 48% jump from the previous week's average and just 10.7% lower than the peak average of 342 children who were admitted to hospitals with the virus that was recorded at the end of August and early September.

In New York City, where cases are surging and the average percent positivity rate is continuing to trend upward, pediatric hospitalizations increased five-fold over a three-week period.

In Chicago, hospitalizations at one children's hospital have quadrupled. At Children's National Hospital in Washington, D.C., close to half the COVID-19 tests are coming back positive.

At Texas Children's Pediatrics & Urgent Care in Houston, the chief medical officer is concerned about the current surge, he said.

"What's concerning on the (pediatric) side is that, unlike the adults -- where they're reporting for the number of adults getting infected relatively low numbers getting hospitalized — what we're really seeing, we think, is an increasing number of kids being hospitalized," Dr. Stanley Spinner said.

Children are an easy target for the virus, said Dr. Juan Salazar, physician in chief at Connecticut Children's Medical Center in Hartford.

"It's affecting larger communities and it's certainly affecting children in a way that we hadn't seen before," he said. "And that's new compared to last year."

CDC updates isolation guidelines

Days after updating its guidance on isolation time for health care workers who test positive for COVID-19, the CDC updated its guidance for the general population.

The agency shortened the recommended time for isolation for people with COVID-19 to five days, if asymptomatic, followed by five days of wearing a mask when around others. The prior guidance advised 10 days of isolation.

"The change is motivated by science demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after," the CDC said in a statement about the updated guidelines.

The new recommendations will allow asymptomatic people "to come back to work earlier, and safely, at very low risk," said Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center.

"That will help us in the New Year begin to get our gears back into operation and to function better."

The CDC also updated its recommended quarantine period for those exposed to someone with COVID-19.

For those who are unvaccinated, have not had a second mRNA dose in more than six months or have not had a booster shot, the CDC recommends quarantining for five days followed by strict mask use for an additional five days.

People who have gotten their booster shot do not need to quarantine if they are exposed to COVID-19, but they should wear a mask for 10 days after exposure, the CDC said.

The shorter isolation and quarantine guidelines stem from "the extraordinary, unprecedented wave of infections" the United States is seeing and is likely to continue seeing over the next weeks, Fauci told CNN on Tuesday.

"There is the danger that there will be so many people who are being isolated who are asymptomatic for the full 10 days that you could have a major negative impact on our ability to keep society running," he said.

The omicron variant of coronavirus is spreading quickly in several countries where it has been discovered. Even if it causes only mild disease — and that's far from certain — that could still mean many people end up in the hospital and dying.

It's killed at least one person in the U.K. and put 10 into the hospital — most of them vaccinated, according to government authorities.

"It is spreading faster than the delta variant in South Africa where delta circulation was low, but also appears to spread more quickly than the delta variant in other countries where the incidence of delta is high, such as in the United Kingdom," the World Health Organization said in a technical briefing last week.

"Given the current available data, it is likely that omicron will outpace the delta variant where community transmission occurs," WHO added.

It's not clear how severe the new variant is, although most cases that have been diagnosed so far have been mild. That could be reassuring, but if omicron spreads more easily than delta and previous variants, evades the protection offered by vaccines and by previous infection, and ends up infecting more people, that could mean more people end up in the hospital and more die.

"What we now know about omicron is that ... it's spreading at a phenomenal rate, something that we've never seen before. It's doubling every two to three days in infections," U.K. Health Secretary Sajid Javic told Britain's Sky News Monday. "That means we're facing a tidal wave of infection. We're once again in a race between the vaccine and the virus."

A new study out Monday from researchers at Oxford University adds to evidence that two of the main vaccines deployed against COVID-19 — the AstraZeneca vaccine used widely in Britain and around the world but not in the U.S., and the Pfizer/BioNTech vaccine used widely in the U.S., Europe and elsewhere — won't protect people as well against the omicron variant.

"Our findings show that vaccine effectiveness against symptomatic disease with the omicron variant is significantly lower than with the delta variant," the researchers wrote.

Infecting both the vaccinated and the boosted

Several reports indicate at least some of those infected with omicron have been both fully vaccinated and boosted, and tests against blood samples from vaccinated and boosted people indicate the same thing.

What this may indicate is that vaccination and especially booster shots provide good protection against severe disease with the omicron variant, doctors say -- although it is far too soon to know for sure. Health officials note many of the first cases have been seen among travelers and people who might be in good health and who might take other precautions.

Disease modelers at the London School of Hygiene and Tropical Medicine released a report Saturday that projects infections in England passing last winter's peak in terms of daily numbers. This could translate into double the number of daily hospital admissions as seen last year, they wrote in a pre-print report posted online.

What's really uncertain is what omicron will do to more vulnerable people, who are unlikely to be among the first infected, but who will eventually see the virus come their way. This might include the elderly, people with varying levels of immune compromise and those with pre-existing medical conditions.

Seeking out the susceptible

"This virus will eventually seek out and land on the people who are the most susceptible, and those are the ones that have not been vaccinated, A, and also the ones that have not been boosted. It's not a matter of if. It's a matter of when," Los Angeles internal medicine specialist Dr. Jorge Rodriguez told CNN.

"High numbers can still mean many people in the hospital," Dr. Crystal Watson, a senior associate at the Johns Hopkins Center for Health Security, told CNN.

While only a few cases have been identified in the U.S. so far, there is little reason to think it will not spread in the U.S. as it has elsewhere.

Houston officials said last week the omicron variant had been detected in wastewater there, although it had not yet turned up in tests of people diagnosed with the virus. That could indicate quiet community spread — something that would not be surprising for a variant that causes mild symptoms or no symptoms. WFTV reported similar findings in central Florida but quoted Altamonte Springs city manager Frank Martz as saying detecting any genetic material from the virus indicated more than one person in the area was infected with the variant.

Even without omicron adding to the spread, the delta variant combined with an undervaccinated population, is doing plenty of damage.

The U.S. passed 50 million reported cases of coronavirus infection Monday and is fast approaching 800,000 deaths.

The CEOs of several health care systems in Minnesota signed a full-page newspaper ad begging people to get vaccinated.

"Our emergency departments are overfilled, and we have patients in every bed in our hospitals," the ad read. "Your access to health care is being seriously threatened by COVID-19. We need to stop the spread!"

It urges people to get vaccinated and boosted, to wear masks and to get tested for the virus.

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.

CINCINNATI —

Even before omicron is detected in the tri-state, it’s already having an impact as it becomes one of the leading reasons for increasing vaccine demand.

The upcoming holidays are still at the top of the list, but omicron has also become a major motivator.

“We kept hearing about the variant,” said Tisha Neblett.

She and her husband got their booster shots at the Hamilton County Health Department operation in Norwood Friday. They’ve seen the worst of COVID-19.

“This COVID thing is real close and personal to me because I had a twin brother die of complications of COVID,” said Dale Neblett.

His twin died last December before vaccines were available. It’s made his discussion with unvaccinated friends very direct.

“I’ve talked to people, and I’ve said ‘if that’s what you want to do, you need to talk to the undertaker first,’” Neblett said.

The fast spread of omicron has many concerned. However, scientists say the spread of a new variant doesn’t necessarily mean it has to be more problematic.

“In theory, if it turns out this is highly transmissible but less virulent, less aggressive, that might actually be a good thing,” said TriHealth Dr. Stephen Blatt.

Blatt is an infectious disease expert. He said, if a variant is more contagious, it could replace the more deadly variant and make people less sick.

“That’s what some people have been predicting, that eventually, this virus would become what we call endemic,” Blatt said. “That would be the best of all worlds if it didn’t cause severe disease, maybe we wouldn’t have to worry about it as much.”

It’s far too early to tell if omicron is that variant.

Delta has been more contagious and has had similar rates of severe disease as the original version of COVID-19.

Omicron has replaced delta as the most dominant virus in South Africa, but there isn't enough information to be reliable about the rate of transmission or how sick people might become.

So far, those tracked with omicron have not had severe disease, but the sample size is small and made up of a young population that is generally less affected by COVID-19.

Just when we thought U.S. travel rules were starting to stabilize, along comes omicron.

The dominoes fell quickly after South African health authorities informed the world of their discovery of the omicron variant of the coronavirus on Nov. 26.

The Biden administration rolled out controversial travel bans on arrivals from eight nations in southern Africa. Travelers found themselves unexpectedly stranded. And now U.S. officials have said they will be tightening travel regulations again.

Things are changing by the day and even by the hour, but here are some of the questions people have about U.S. travel rules — and answers we have right now:

Are testing rules for entry into the US changing?

Yes, according to President Joe Biden's announcement on Thursday of new measures aimed at curbing the pandemic.

All inbound international travelers will soon be required to test within one day of departure for the United States.

This new time frame will apply to everyone, "regardless of nationality or vaccination status," the plan outlined on the White House website says.

According to the plan posted, the tightening of the testing protocol will happen "early next week."

Currently, vaccinated travelers are required to test within three days of their departure. There is a requirement for foreign travelers arriving in the United States to be fully vaccinated.

Unvaccinated Americans and legal permanent residents are allowed to enter the country with a test taken within one day of departing for the United States. The new rule will make the testing time frame one day for everyone.

Biden also announced that the federal mask mandate requiring travelers to wear masks in airports, on planes and on other modes of public transportation such as trains and buses has been extended through March 18.

Is there a post-arrival testing or quarantine requirement?

There is not. "We're not announcing any steps on post-arrival testing and quarantine," a senior administration official said in a press briefing on Wednesday evening.

"I will say — look, if additional measures are recommended, if additional measures can be implemented well and are effective, we won't hesitate to take them, but we're not taking them today," the official said, according to a White House transcript of that briefing.

What countries fall under the new US travel ban?

The travel bans announced on Nov. 26 bar entry into the U.S. of noncitizens coming from eight countries in southern Africa. They are Botswana, Eswatini, Lesotho, Malawi, Mozambique, Namibia, South Africa and Zimbabwe.

On Nov. 27, the CDC placed them all at Level 4 "very high" risk for COVID-19. (Botswana was already at Level 4 because of its caseload — more than 500 per 100,000 residents in the past 28 days.)

Citizens of those nations and citizens of other nations who have been traveling there in the past 14 days are currently not allowed entry into the United States.

Can US citizens already in those nations return?

Yes, they can.

Per the White House proclamation, the CDC says that "citizens and lawful permanent residents of the United States, certain family members, and other individuals who meet specified exceptions, who have been in one of the countries listed above in the past 14 days will be allowed to enter the United States."

As of Dec. 2, they still had to follow the rules already in place to re-enter: A negative result from a COVID-19 test within three days of travel if fully vaccinated and within one day of travel if unvaccinated.

Can US citizens still travel to the banned nations?

Technically, yes.

At least two U.S. carriers are still flying back and forth from South Africa. Delta Air Lines is still offering Atlanta-Johannesburg service, and United Airlines is still offering Newark-Johannesburg service.

United Airlines is also resuming nonstop service between Newark and Cape Town, according to a news release from South African Tourism. The release also said, "we would like to emphasize that our country remains open for all those travelers who wish to visit."

Whether it's advisable to go is another matter. The CDC advises against it.

You might also encounter new travel barriers. For instance, Zimbabwe imposed a lockdown and mandatory quarantine on Nov. 30, for travelers, state-run news agency NewZiana reported.

Going to southern African nations while bans are in place around the world might cause you to be banned from going to other countries. For instance, the United Kingdom is not allowing anyone who has been to "red list "countries — which include Angola and Zambia as well as the eight discussed above — from entering except its own returning citizens.

Argentina, Canada, Italy and other nations also have put bans in place, each with their own specific parameters.

What is the US doing to detect the virus?

The CDC said it would expand omicron surveillance at four major U.S. international airports.

The CDC also confirmed to CNN on Wednesday that officials have directed airlines carrying passengers that have been to certain southern African nations to share those passengers' contact information with the agency.

Airlines have already been gathering contact information from passengers under a CDC contact tracing order that has been in effect since Nov. 8.

CINCINNATI —

Preparation is everything according to health experts as the new variant, omicron, continues to spread across the globe.

The tools we do have, masking, social distancing and getting vaccinated, are what health experts are recommending as we wait to find out more information about omicron and its transmissibility, how sick it makes us and if our current vaccines work effectively against it.

"People panic and what we need to do is focus on another p-word and that is preparation," UC Health's College of Medicine Dr. Lou Edje said.

Karl Hosterman got his booster shot with the Hamilton County Health Department Tuesday afternoon.

"I guess the jury is still out about whether the vaccine is going to work against the variants," Hosterman said.

That's true when it comes to this omicron variant, according to Edje.

As for the delta variant, which is still most widespread in the U.S., she said that the third shot is proven to help.

"We do know that the boosters that we have give you a thirty to 40-fold increase in virus-neutralizing antibodies that is huge," Edje said.

Getting your 5 to 11-year-old's vaccinated is also crucial as we wait to learn more about omicron.

What we have heard this entire pandemic is the way to get out of this thing is by getting everybody vaccinated so as soon as the vaccine became available for our kids we signed up," Alex Linser of Mt. Washington said.

Pediatrician Chris Peltier with Pediatric Associates of Mt Carmel agrees.

"I still have probably a quarter to maybe a third of my practice that's ineligible and can't get vaccinated so we need to protect our youngest patients," Peltier said. "We see less severity of disease in kids so hopefully that would continue with this new variant although we just don’t have experience to say that."

BRUSSELS —

New findings about the coronavirus's omicron variant made it clear Tuesday that the emerging threat slipped into countries before their defenses were up, as two distant nations announced their first cases and a third reported its presence before South African officials sounded the alarm.

The Netherlands’ RIVM health institute found omicron in samples dating from Nov. 19 and 23. The World Health Organization said South Africa first reported the variant to the U.N. health agency on Nov. 24. Meanwhile, Japan and France reported their first cases of the new variant that has forced the world once again to pinball between hopes of returning to normal and fears that the worst is yet to come.

Much remains unknown about the new variant, including how contagious it might be, but a WHO official said Tuesday that there could soon be a steep rise in infections in parts of southern Africa.

It is unclear where or when the variant first emerged, and the Dutch announcement further muddies the timeline. Previously, the Netherlands had said it found the variant among passengers who came from South Africa on Friday — but the new cases predate that.

That hasn’t stopped wary nations from rushing to impose travel restrictions, especially on visitors coming from southern Africa. Those moves have been criticized by South Africa and the WHO has urged against them, noting their limited effect.

The latest news though made it increasingly clear that travel bans would struggle to stop the spread of the variant. The Netherlands, Belgium and France have now all reported cases in people who were in their countries before the European Union imposed flight restrictions.

Japan announced that it would ban all foreign visitors beginning Tuesday — but that turned out to be too late. It confirmed its first case that day, a Namibian diplomat who recently arrived from his country.

German authorities, meanwhile, said they had an omicron infection in a man who had neither been abroad nor had contact with anyone who was.

The WHO warned Monday that the global risk from omicron is “very high.” and that early evidence suggests it could be more contagious.

The growing number of cases attributed to omicron in Botswana and South Africa suggests that this may be the first sign of a “a steep rise,” Dr. Nicksy Gumede-Moeletsi, regional virologist for the World Health Organization, told The Associated Press on Tuesday.

“There is a possibility that really we’re going to be seeing a serious doubling or tripling of the cases as we move along or as the week unfolds,” Gumede-Moeletsi said.

After a period of low transmission in South Africa, new cases began to rapidly increase in the middle of November. Currently the country is confirming nearly 3,000 new infections per day.

The concentration of omicron cases among university students in the capital of Pretoria is a particular cause for concern because that group is very sociable — and will soon be heading for their homes at the end of the year and mixing with friends and family.

Doctors in South Africa are reporting patients are suffering mostly mild symptoms so far, but many of them are young adults who generally do not get as sick from COVID-19 as older patients.

Still, many officials tried to calm fears, insisting vaccines remain the best defense and that the world must redouble its efforts to get the shots to every part of the globe.

European Medicines Agency chief, Emer Cooke, insisted that the 27-nation EU was well prepared for the variant. While it is not known how effective current vaccines are against omicron, Cooke said the shots could be adapted within three or four months if need be.

The latest variant makes vaccination efforts even more important, U.S. Secretary of State Antony Blinken said, noting as many have before that “as long as the virus is replicating somewhere, it could be mutating.”

In the face of the new variant, some introduced new measures aimed at mitigating the spread.

England made face coverings mandatory again on public transport and in shops, banks and hairdressers. And one month ahead of Christmas, the head of the U.K.’s Health Security Agency, Jenny Harries, urged people not to socialize if they don’t need to.

And after COVID-19 already led to a one-year postponement of the Summer Games, Olympic organizers were beginning to worry about the February Winter Games in Beijing.

Chinese Foreign Ministry spokesperson Zhao Lijian said omicron would “certainly bring some challenges in terms of prevention and control.”

World markets continued to seesaw on every piece of medical news, either worrisome or reassuring.

Global shares mostly slipped Tuesday as investors cautiously weighed how much damage omicron may unleash on the global economy.

Some analysts think a serious economic downturn, like what happened last year, likely will be averted because many people have been vaccinated. But they also think a return to pre-pandemic levels of economic activity, especially in tourism, has been dramatically delayed.

In a world that is already unnerved by the more contagious delta variant that filled hospitals again in many places, even in some highly vaccinated nations, the latest developments underscored the need for the whole globe to get their hands on vaccines.

“We have vaccination rates in the United States, in Europe of 50, 60, 70 %, depending on exactly who you’re counting. And in Africa, it’s more like 14, 15 % or less,” Blinken said.

“We know, we know, we know that none of us will be fully safe until everyone is.”

___

Meldrum reported from Johannesburg. AP journalists from around the world contributed.

The U.S. Centers for Disease Control and Prevention strengthened recommendations for booster doses of coronavirus vaccine Monday, saying all adults should get boosted six months after the second dose of Pfizer/BioNTech's or Moderna's vaccine or two months after the single-dose Johnson & Johnson vaccine.

It's a slight but significant tweak to the wording of guidance issued earlier this month when the CDC endorsed an expanded emergency use authorization for boosters from the U.S. Food and Drug Administration.

"Today, CDC is strengthening its recommendation on booster doses for individuals who are 18 years and older," CDC Director Dr. Rochelle Walensky said in a statement.

"The recent emergence of the Omicron variant (B.1.1.529) further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19," she added.

"Early data from South Africa suggest increased transmissibility of the Omicron variant, and scientists in the United States and around the world are urgently examining vaccine effectiveness related to this variant. I strongly encourage the 47 million adults who are not yet vaccinated to get vaccinated as soon as possible and to vaccinate the children and teens in their families as well because strong immunity will likely prevent serious illness."

Previously, the CDC said people should get a booster if they are 50 and older, or 18 and older and living in long-term care. Otherwise, it is advised that anyone 18 and older may get a booster. Now the word "should" applies to everyone 18 and older.

It will take a few weeks of testing to know for sure whether the omicron variant is more transmissible than delta, and whether it evades the protection offered by natural infection or vaccines. Scientists will also be looking to see if it causes more severe disease or evades the effects of treatments.

In the meantime, CDC will be watching for omicron to appear in the U.S. That requires an extra step of testing as the tests used to diagnose COVID-19 won't tell people which variant they are infected with. "I also want to encourage people to get a COVID-19 test if they are sick. Increased testing will help us identify Omicron quickly," Walensky said.

"And finally, to stop the spread of COVID-19 we need to follow the prevention strategies we know work," she added. These include vaccination, wearing masks, improving ventilation indoors and keeping a distance from others, especially if they are unvaccinated.

As the world waits to learn how the omicron variant might impact the global COVID-19 pandemic, it's easy to get caught up in the unknowns. Instead, health officials are reminding us of the simple yet effective tools we all have to combat the virus.

Here's a refresher on how to protect yourself and your loved ones.

Get vaccinated

Getting vaccinated is one of the best ways to protect yourself and those around you. Vaccines are readily available across the U.S. and many Americans are now eligible for a booster shot.

"Get your vaccine, get your booster," Dr. Francis Collins, director of the National Institutes of Health, told CNN. "It's the best chance we've got to drive this COVID-19 pandemic away."

Vaccines have proven to be safe and effective at reducing severe COVID-19 cases.

Wear a mask properly

It's simple, but wearing a mask properly is one of the most important ways you can protect yourself and those around you, health experts say.

N95 masks offer the best protection. Washable, breathable cloth masks will do the job, but they should have at least two layers — three are better — and you can add a filter for more protection.

Masks should cover both your nose and mouth, and should fit snugly, with no gaps.

Goggles or face shields aren't necessarily recommended for eye protection if you are not a health care worker or are in high-risk situations, health experts have said.

Check for symptoms and get tested

Fever, coughing and shortness of breath are among the most common symptoms of COVID-19, the disease the coronavirus causes.

But there's also diarrhea, nausea and vomiting, fatigue, loss of smell and taste, body aches, mental confusion and even delirium.

Have a runny or stuffed-up nose? Unless you have a fever, it's probably just allergies, such as can be caused by leaf mold at this time of year.

If you have been exposed to the coronavirus, symptoms will probably show up within a week, health experts say. That is, if you are going to have them at all — which some people don't. Any or all symptoms can appear between two and 14 days after exposure to the virus, according to the U.S. Centers for Disease Control and Prevention.

If you suspect you have been infected, go to a testing center near you. Contact your local or state health department to find out where to get a test.

Serious symptoms include difficulty breathing, persistent pain or pressure in your chest, new confusion, the inability to stay awake or wake up and bluish face or lips, according to the CDC.

Wash your hands

Washing your hands frequently is still one of the most basic and simple things you can do.

Work up a good lather and scrub your hands, fingers and under your nails for at least 20 seconds. Use clean, running water to thoroughly rinse, then scrub them dry.

Washing for at least 20 seconds has been shown to remove more microbes than washing for shorter periods. Singing "Happy Birthday" twice while washing can work as a "timer."

Frequent handwashing will also protect you from all sorts of harmful bacteria and viruses other than the new coronavirus, including influenza and the common cold.

Use hand sanitizer

It's not as good as washing your hands with good old soap, but hand sanitizer can be used when soap isn't an option.

It's important both of your hands are covered completely, including between the fingers and under the nails. Rub your hands until they are dry. Use it generously if your hands are greasy or really dirty since the sanitizer might not be as effective in that case, according to the CDC.

Unlike at the beginning of the pandemic, hand sanitizer is relatively easy to find in stores, so don't try to make your own. Health experts say it's critical you get the right concentration of alcohol to disable the virus.

Reduce your risk

The best thing you can do is stay home, if possible, and reduce your risk by cutting down on errands and trips to the store.

Not everyone has the luxury of doing it, of course, but social distancing — keeping 6 feet between you and others outside your household — and wearing a mask are critical.

The safest place outside your home is the outdoors. But even there, you should keep a safe distance from people you don't live with.

You can also reduce risk by getting take-out food instead of dining in restaurants and avoiding public transportation, if possible.

SACRAMENTO, Calif. —

A new coronavirus variant first detected by scientists in South Africa has brought concerns and questions for many people.

It's unclear where the new variant actually came from, but it was first detected by scientists in South Africa and has also been seen in travelers to Hong Kong and Botswana.

Health experts say this variant may be more dangerous than the delta variant, which has fueled waves of infection on every continent. This new variant has already sparked travel restrictions, shaken up world markets and has scientists scrambling to understand the risks.

Americans often get a flu shot every year because of different strains, and some are wondering if we'll have to get more COVID-19 boosters because of the new variant.

Dr. Vanessa Walker of Pulmonary Medical Associates said we may just have to wait and see.

"It's going to take time for us to see how this plays out to see whether or not we need boosters more frequently than you would typically expect, like we do with influenza," Walker said.

"The reason why it might be more likely that it would be the case is because with influenza we get a break, right? It goes around. It is seasonal. COVID isn't seasonal. It's always there. It's always going to be there, unfortunately," she added.

Dr. Dean Blumberg, UC Davis pediatric infectious disease expert, also said it was unclear how long the protection from the vaccine could last.

"We are just at the beginning of how immunization protects against COVID. We know it protects very well, but we are still not sure if the optimal initial series is a two-shot or three-shot series and how long that is going to last," Blumberg said.

He added that it's unknown how often we may end up needing boosters.

"Whether we will need boosters every year or every 10 years, or whether the boosters will need to be changed and adapt to the current circulating strains, these are all questions and we just don't have answers yet,” he said.

As the new COVID-19 omicron variant spurs global travel bans, experts say concerns over its impact should prompt millions of unvaccinated Americans to get their shots — and for those who are eligible, to get their boosters.

"I would hope that within the next week or two weeks, so many of those people will take advantage of the vaccine," Dr. William Schaffner, a professor at Vanderbilt University Medical Center, told CNN on Friday. "That will help us in the immediate term. And I would anticipate that, as bad as Omicron might be, our vaccine still will be partially effective."

Dr. Anthony Fauci echoed that, pointing to vaccinations and boosters as effective mitigation tools.

"I'm saying this absolutely clearly, that if ever there was a reason for unvaccinated people to get vaccinated and for those who have been vaccinated when your time comes up to go and get a booster shot," Fauci told NBC News on Friday.

"The booster shots give you a very, very important edge," he said, noting that boosters increase the level of antibodies that protect against the virus.

Data from the U.S. Centers for Disease Control and Prevention shows that 196 million Americans, or 59% of the U.S. population, was fully vaccinated as of Friday. An additional 37.5 million have received booster shots, the data shows.

On Friday, the U.S. moved to restrict travel from eight mostly southern African countries starting Monday as the World Health Organization deemed omicron, first detected in South Africa, a variant of concern. Travel into the U.S. will be restricted for those entering from Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, Mozambique, Malawi and South Africa.

Omicron has raised concerns for health officials because there's a possibility it could be more contagious than the original novel coronavirus strain, the WHO said, and it also has a significant number of mutations.

After a pandemic that has lasted nearly two years, experts and global leaders are anxious about the impact of the omicron variant, and many nations have issued travel bans. Besides South Africa, the newly identified variant has been detected in Botswana, Hong Kong and Belgium.

Two cases of the variant have also been detected in the U.K., Secretary of State for Health Sajid Javid said Saturday, prompting British Prime Minister Boris Johnson to announce a series of "targeted" measures to combat the variant.

There have been no indications so far that the variant has made its way into the U.S., Fauci told CNN Friday. On Saturday morning, however, he told NBC he "would not be surprised" if the variant was already in the U.S., saying, "it almost invariably is going to go all over."

The U.S. variant surveillance system has reliably detected new variants in the past, the CDC said.

"We expect omicron to be identified quickly, if it emerges in the U.S.," the agency said in a statement.

Vaccine makers are working to determine effectiveness against omicron

Meanwhile, vaccine makers have disclosed they are taking action to address the emergence of a new variant.

Moderna is working quickly to test the ability of its vaccine to neutralize omicron, the company said Friday, and data is expected in the coming weeks.

The strain includes mutations "seen in the Delta variant that are believed to increase transmissibility and mutations seen in the Beta and Delta variants that are believed to promote immune escape," Moderna said in a news release.

"The combination of mutations represents a significant potential risk to accelerate the waning of natural and vaccine-induced immunity."

If its current vaccine and booster are insufficient against the variant, Moderna explained that one possible solution is boosting people with a larger dose, which the company is testing.

The company is also evaluating two multivalent booster candidates to see if they provide better protection against omicron — both of which include some of the viral mutations present in the variant. Moderna said it is also testing an omicron-specific booster.

"For several days, we have been moving as fast as possible to execute our strategy to address this variant," Moderna CEO Stéphane Bancel said in the news release.

Scientists at BioNTech, the German company that partnered with Pfizer to make its COVID-19 vaccine, are also investigating the impact of the variant on their shot, with data expected within the upcoming weeks.

A Johnson & Johnson spokesperson told CNN in a statement the company was also testing the effectiveness of its vaccine against omicron.

COVID-19 travel restrictions aren't all that effective, experts say

The Biden administration's decision to curtail travel from eight countries is a precautionary measure as the U.S. government learns more about the Omicron variant of coronavirus.

But some experts say travel restrictions aren't as effective as they may seem.

"Travel bans are modestly effective. They can obviously influence travel directly from that country to the United States," said Schaffner, the doctor at Vanderbilt University Medical Center.

"But obviously U.S. citizens will be permitted to come back. They could bring the virus. And people could go from the country of interest, South Africa for example, and go to other countries that are not on the travel ban, and enter, if you will, by the side door. So travel bans are somewhat effective, but let's not expect a miracle," he said.

U.S. citizens, lawful permanent residents and noncitizens who are the spouses of citizens or permanent residents are exempted from the new restrictions.

Dr. Megan Ranney, a professor of emergency medicine and Associate Dean of Public Health at Brown University, said universal vaccination requirements for all air travel would be more effective.

"Or having quarantines when people arrive in the U.S. from other countries. Neither of those are particularly politically palatable right now, but they would make a much bigger difference in the spread of this variant," Ranney told CNN on Friday.

The Centers for Disease Control and Prevention has once again overhauled its mask guidance this week, asking all Americans to go back to wearing face masks in indoor public spaces and in crowded outdoor areas, regardless of vaccination status.

The agency's new mask recommendations come as the delta variant of COVID-19 continues to spread, leading to an uptick in new coronavirus cases across the United States. And since vaccines are still being observed in trials for children under 12, CDC officials also updated guidelines asking all students in grades K-12 to mask up while in school this fall.

The delta variant is more contagious than other forms of COVID-19. People infected with this strain may carry up to 1,000 times more viral airborne particles in their airways than those infected with earlier versions, according to emerging data. While vaccines prevent most to all of the deadly symptoms associated with COVID-19 illnesses, CDC officials did also recently acknowledge that vaccinated people can indeed spread the disease to others around them.

"The best recommendation would be, regardless of vaccination status, to continue wearing a mask to protect your loved ones and yourself against COVID as an added layer of protection," said Dr. Vivek Cherian, an internal medicine physician affiliated with the University of Maryland Medical System.

But if you're still wearing the same face masks you rushed to purchase (or even sew yourself) back in the early months of the pandemic, it's important to know these masks are likely less protective than other options available now.

What's the best mask to protect against the delta variant?

Cloth masks made in the first half of 2020 weren't designed as stringently as they are now, and it wasn't until late 2020 and early 2021 that CDC officials began making more stringent mask recommendations to Americans (like in January, when officials asked Americans to consider double-masking). While cloth masks certainly are better than no mask at all when it comes to preventing the spread of COVID-19, the fit and construction of medical-grade surgical face masks are usually more comprehensive — and currently, they're readily available for consumers.

Good Housekeeping Institute Textiles Director Lexie Sachs said that surgical masks are usually made by PPE manufacturers who adhere to strict quality standards that have been in place since long before the pandemic began.

"We know they're typically safer in terms of filtration and fit," Sachs added, as opposed to cloth masks made by fashion retailers who don't usually deal with medical standards in construction. "They're often more breathable as well."

Most crucially, you can rest assured that the medical-grade surgical mask you're wearing is tested to meet standards set forth by ASTM International, an industry group in charge of establishing safety minimums for many products, including face masks.

"You'll know whether or not it's been tested to meet standards — in this case, ASTM Level 3 and more — rather than blindly guessing with most cloth options," Sachs said.

There are also N95 and KN95 masks, otherwise known as respirators, which are known to be more protective than surgical masks. Why? Because they're carefully engineered to prevent large and small airborne particles from specifically penetrating the masks' front. Mayo Clinic officials clarify that while surgical masks can indeed offer filtration on par with or superior to cloth masks, they are primarily designed to prevent fluids and sprays from landing on the wearer in a clinical setting — not particles or aerosols.

While N95 and KN95 masks were largely unavailable at the start of the pandemic — and officials at the Food and Drug Administration still maintain that PPE supply levels are low in crucial categories like respirators — there are more respirator masks available now than there were at the beginning of the outbreak.

In fact, Scott Gottlieb, a former FDA commissioner, recently advised Americans to consider wearing N95 or KN95 masks, sourced from China, to best protect themselves from COVID-19 exposure in public. "If you're going to consider wearing a mask, the quality of the mask does matter," Gottlieb told CBS reporters. "So if you can get your hands on a KN95 mask, or an N95 mask, that's going to afford you a lot more protection."

"There's no question that [respirators] offer the best protection as they fit more securely and also offer high filtration abilities if you are able to secure those masks," Cherian said. "However, cloth masks are still an effective option [if you can't find a respirator]."

What's the best mask for my child to wear?

As N95s are classified as a respirator, you'll need to fit them tightly across your nose and mouth to ensure proper filtration and effectiveness. Product manufacturers usually include directions for mask wearers to ensure they're using an N95 or KN95 correctly, but depending on which respirator you choose, it may be harder to fit the mask properly, explained Dr. Charles C. J. Bailey, an infectious diseases specialist at Providence Mission Hospital in California.

Because of their encompassing fit, Bailey and other experts caution against children using an N95 or KN95. Respirators can be much harder to breathe in than medical masks or cloth masks, which is especially challenging for kids in active settings or during physical activity. Surgical masks are better suited for children, especially those with respiratory issues or who are particularly active, over ill-fitting N95 or KN95 masks.

Bailey adds that keeping a perfectly fitted N95 or KN95 on a child would be an impractical challenge, and wearing an ill-fitting respirator won't offer any extra protection over other mask choices (this is also true for adults!). Remember: CDC officials still recommend that any child under the age of two refrain from all masks at this time, including those children with pre-existing respiratory conditions that make masks potentially harmful.

How can I shop for the best mask moving forward?

If you're still using the same cloth masks you purchased in 2020, it may be time to consider swapping them out for a respirator or surgical mask — or, at the very least, a newer cloth-based mask, Sachs said.

"The shelf life of a cloth-based mask is typically based on the number of washes, and the brands that conform to ASTM standards should be telling customers this information," she added.

New ASTM International standards were drawn up to give designers and lifestyle brands more direction in creating safer non-PPE cloth face masks. These standards ensure the mask will properly fit over your nose and mouth, can filter airborne particles effectively, and are reasonably breathable for consumers, among other concerns. The Unicorn Breathing Mask is an example of a cloth mask that claims to have been tested and manufactured according to ASTM standards — you'll see clear language indicating this on the brand's digital storefront.

Manufacturers are slowly adapting the way they make their masks so they can meet the standards set forth by the ASTM; if a favorite mask of yours doesn't yet display any ASTM classification, it may be that the masks aren't made sufficiently protective to qualify, Sachs explained.

It's also always best to buy new face masks rather than try to repair a torn or stretched face mask. And if anything is clear, it's that the investment in properly constructed face masks will pay off in the end — it looks like these current CDC guidelines will be in place until all children become eligible for vaccines, and possibly until an overwhelming majority of Americans choose to sign up for a vaccine.