The news comes as the number of average daily COVID cases in the U.S. has in the past two weeks, and as fears for spread of the Omicron variant have motivated a to a level not seen since late May. 

“With both the Delta and Omicron variants continuing to spread, vaccination remains the best protection against COVID-19,” said Acting FDA Commissioner Janet Woodcock in a .

The Omicron strain, listed as a “variant of concern” by the World Health Organization in late November, currently makes up a miniscule fraction of U.S. infections, but features a combination of mutations that worries scientists. It is known to have infected more than , the director of the Centers for Disease Control and Prevention told the Associated Press Wednesday.

The first look at how vaccines hold up against the Omicron variant bodes well for the efficacy of Pfizer-BioNTech’s booster doses, experts say. 

Lab data published Tuesday analyzing how effectively blood from vaccinated South Africans neutralized the new strain found that the virus did evade the immune defenses more craftily than previous versions of COVID. However, blood from individuals who had a previous infection and then received two vaccine doses did a good job staving off Omicron. It’s the best proxy so far for the immunity of those who have received three doses, scientists say, because South Africa has not yet authorized booster shots.

“​​This study gives me great hope that our boosters will help protect against Omicron,” Katelyn Jetelina, an assistant professor of epidemiology at the University of Texas School of Public Health, wote in a explaining the new lab results.

In authorizing third doses for 16- and 17-year olds, the FDA expanded its already existing emergency use authorization for the Pfizer-BioNTech vaccines to include older teens. Before shots can be officially administered to the newly eligible group, they need to receive the green light from the CDC, an authorization that is expected to come swiftly. The federal agency cleared boosters for all adults 18 and older in early November.

“Since we first authorized the vaccine, new evidence indicates that vaccine effectiveness against COVID-19 is waning after the second dose of the vaccine for all adults and for those in the 16- and 17-year-old age group,” said Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research. “A single booster dose of the vaccine for those vaccinated at least six months prior will help provide continued protection against COVID-19 in this and older age groups.” 

Meanwhile, as many Americans are still wrapping their minds around first, second and third doses, Pfizer CEO Albert Bourla said late Wednesday that the Omicron variant could mean will be necessary in under 12 months.

New Mexico appears to be the first state to require that certain workers receive booster shots, including a vaccinate-or-test rule for K-12 staff. So far, about 9 percent of school employees statewide have submitted documentation of having received a third dose.

Ensuring that staff and eligible students up their immunity as Omicron threats loom may be of particular importance given that temporary school closures have continued through the fall. Roughly 10 percent of the nation’s schools have experienced a disruption this school year alone. Some closures have been due to outbreaks, but others have been caused by teacher burnout and staffing shortages.

As of Dec. 1, some 4.3 million children ages 5 to 11, representing 15 percent of the age group, had received a vaccine dose. The same was true for ages 12 to 17, and over half had completed the full two-dose series, according to data published by the American Academy of Pediatrics.

Across all ages, more than people in the U.S are now fully vaccinated, about 60 percent of the population.

In what may be a national first, New Mexico issued a requiring that all school staff receive coronavirus booster shots or submit to weekly testing.

The state was already enforcing a vaccinate-or-test rule for K-12 workers and other state employees, but due to concern surrounding the recently identified Omicron variant, the state announced that it will require school staff to up their immunity with an extra shot of the vaccine by Jan. 17, 2022. 

Booster shots, infectious disease specialists believe, are the against the new strain.

“We recognize the gravity of the situation,” Nora Sackett, press secretary for Gov. Michelle Lujan Grisham, told The 74. “For folks who are fully vaccinated, they are now required to get their booster shot, if they’re eligible.”

As of Nov. 29, 85 percent of school staff had been fully vaccinated, according to the state Public Education Department. K-12 employees who are unvaccinated, or who have two doses but choose not to receive a third, must undergo weekly testing for the virus, she explained. If staff are non-compliant with the testing regimen, individual school districts will decide on repercussions. 

Only about 9 percent of school staff reported having received a booster shot as of Dec. 7, meaning the vast majority of vaccinated K-12 employees still must submit documentation of a third dose by Jan. 17 in order to avoid the state’s weekly testing regimen.

Outside of schools, the order requires third doses with no testing opt-out for New Mexico’s health care workers. It’s the first booster mandate in the nation that the data team behind the has identified.

“We haven’t seen it anywhere else,” Burbio co-founder Dennis Roche told The 74. 

While numerous districts, including Chicago, gave teachers a day off to get their third shots, he said, “we have not seen [boosters] mandated until we saw it in New Mexico.” 

Sackett, also, said she was not aware of any other states having such a policy on the books.

The published by the governor’s office includes multiple paragraphs outlining the threats posed by the Omicron variant, which seem to have motivated the announcement.  The new COVID strain has been detected in at least , with cases continuing to increase, according to the Centers for Disease Control and Prevention. 

In late November, the World Health Organization named the Omicron strain a “variant of concern” just days after it was first identified. Its high number of mutations — including more than the Delta strain on the protein used to latch onto cells — raises alarm for officials. But scientists have yet to determine whether the new version of the virus is indeed more transmissible or better able to evade the protections provided by existing vaccines. More clarity will arrive in the , experts say. For now, the Delta variant remains the dominant coronavirus strain in the U.S. and is responsible for the vast majority of cases, hospitalizations and deaths.

The CDC last Monday on booster doses to recommend that all adults “should,” rather than “may,” receive a third shot six months after their second. A day later, Pfizer CEO and Chairman Albert Bourla announced that his pharmaceutical company from the Food and Drug Administration to extend eligibility for third doses to 16- and 17-year olds.

Alarm over possible threats from the Omicron strain may be translating into more demand for coronavirus immunizations. On Thursday, nearly doses were administered, according to CDC data, a level not seen since late May.

It remains unclear, however, who exactly has been rolling up their sleeves. Counts published by the American Academy of Pediatrics indicate that the number of youth getting vaccinated against the coronavirus had in the seven-day period ending Dec. 1, but the nationwide spike in doses has mostly come after that window.

On Thursday, President Joe Biden announced a spate of new policies designed to enhance school safety and boost youth vaccination rates. He introduced measures including the and a requirement that Medicaid pay health care providers for vaccine consultations with families. 

“​​We’re going to fight this variant with science and speed, not chaos and confusion,” said the president.

Biden also indicated that the CDC would soon release updated guidance on “test-to-stay” programs for schools that allow students potentially exposed to the virus to avoid quarantine if they test negative before the school day. This fall, the practice has grown increasingly popular nationwide as schools seek to keep healthy students learning in person. Test-to-stay schemes would likely expand further should the federal government recommend their implementation.

In California, the state that so far has taken the most aggressive approach to vaccinating its public school students, a federal appeals court on Sunday delivered a win to San Diego Unified School District, against the implementation of its student COVID immunization mandate. Students 16 and up in the state’s second-largest school system will have until Dec. 20 to receive their second vaccine doses if they wish to attend school in person after Jan. 24, when the policy is set to take effect. 

“This latest decision recognizes that we have both the responsibility to protect students and the authority to do so by implementing a vaccine mandate, which is really our best hope as a country to get this deadly disease under control,” Board President Richard Barrera said in a statement.

The case, however, may be ongoing according to Paul Jonna, the attorney representing the lawsuit’s plaintiff, a 16-year-old high school junior who sued the district over its mandate in October, citing religious objections.

“We will seek emergency relief from the U.S. Supreme Court as soon as possible,” Jonna said in a statement.

More than eligible San Diego students are fully vaccinated, the San Diego Union-Tribune reports. 

Just north in Los Angeles, where a student immunization rule will also soon go into effect, the district published figures Nov. 22 showing that of eligible youth had received at least one coronavirus shot or were medically exempt. L.A. Unified’s mandate applies to all students ages 12 and up.

California is also the only state in the nation to adopt a statewide student COVID mandate, which will likely kick in next school year. But already, a small district in San Diego County has said that it will allow unvaccinated students to continue learning in separate, off-campus buildings, .

“For whatever reason, if the parent chooses not to vaccinate [their child], I still believe that a student deserves every opportunity to reach their potential,” schools Superintendent Rich Newman said.

On the other side of the country, New York City will up the stakes on vaccination even for its youngest residents, requiring restaurants and movie theaters by Dec. 14 to of children ages 5 to 11, Mayor Bill de Blasio announced Monday.

Back in New Mexico, bracing for the possible threats of the Omicron variant, acting Health Secretary David Scrase shared his reasoning on the state’s new booster requirement.

“New Mexico isn’t an island,” he said, “and we can’t prevent the new variant from arriving here. So we must defend ourselves with the tools we know to work.”

Even before the World Health Organization labeled the Omicron coronavirus strain a new “variant of concern” Friday, school closures were continuing to increase across the country. 

Last week, 621 schools across 58 districts announced new closures for a variety of reasons including teacher burnout, staffing shortages and virus outbreaks, according to counts from Burbio, a data service that has tracked school policy through the pandemic. Since the start of the academic year, nationwide have added extra days off.

The numbers suggest that nearly 10 percent of the nation’s roughly 98,000 K-12 schools have experienced closures this year. In Maryland, more than 3 in 10 schools have been affected by at least one day of disruption this academic year. In North Carolina, where such events have been most frequent, the number is above 4 in 10.

Now, schools already struggling to keep classrooms open could face further challenges should the recently identified Omicron variant, which has already , fuel a COVID surge this winter. 

“This is only going to make matters worse,” Dan Domenech, executive director of the School Superintendents Association, told The 74. “We already see that most districts are short-handed.”

Earlier in November, lack of substitute teachers forced multiple large school systems to announce unplanned closures as teachers took additional time off around Veterans Day and Thanksgiving.

Shutting down is a last-resort option that schools should seek to avoid, said Domenech. But sometimes it’s school leaders’ only viable choice, he said.

“If they have a staff that’s on the verge of burnout and they keep pushing them, they’re only going to lose more staff. And that’s going to result in more closures and fewer kids being in person.”

Now, with K-12 staff stretched thin in districts across the country, health experts are scrambling to understand the threat posed by the new variant, which Moderna’s President Dr. Stephen Hoge described as having a “” of mutations. 

In South Africa, where Omicron was first identified Nov. 24, the strain has contributed to a sharp spike in cases, leading doctors to believe that it is more transmissible than previous versions of the virus. But whether those cases are more severe, and exactly how much protection is delivered by the vaccines, remains unclear. 

The South African doctor who first discovered the variant told the BBC on Sunday that symptoms have generally been “.” But other experts point out that these initial observations are only based on a very small sample size.

“This variant is a cause for concern, not a cause for panic,” said President Joe Biden in an address to the nation Monday morning.

Health experts, the president said, including Dr. Anthony Fauci, believe that existing COVID vaccines will continue to provide a degree of protection against the new strain, especially for individuals who have upped their immunity through booster shots. But it will be before scientists gain more precise results on just how effectively antibodies built up through vaccination neutralize the Omicron variant, Dr. Kavita Patel, a nonresident fellow at the Brookings Institution, told CNBC on Monday. Still, there’s reason to be hopeful, she said.

“The current vaccines don’t just generate the variant-specific antibodies. They try to generate kind of a broad antibody response,” said the Washington, D.C.-based physician.

Because of the Omicron variant, the Centers for Disease Control and Prevention on Monday on booster doses to recommend that all adults “should,” rather than “may,” receive a third shot six months after their second. Meanwhile, The Washington Post reported Monday evening that Pfizer-BioNTech plans to for 16- and 17-year olds, after initial booster data out of Israel showed positive results within that age group.

While the details of the new variant come into focus, Atlanta-based pediatrician Jennifer Shu said K-12 buildings need to keep their guard up to stave off in-school transmission.

“It’s important for schools to continue protective measures such as masking, hand washing, physical distancing when possible, disinfecting, optimizing ventilation, etc. to limit the spread of COVID-19,” the doctor wrote in an email to The 74.

At this point, Domenech said he is not aware of any school leaders within his network having changed their safety procedures in response to the emergence of the Omicron variant.

Over the course of this school year, many districts have moved to introduce ‘test-to-stay’ measures that allow students potentially exposed to the virus to skip quarantine, provided they test negative for COVID on a rapid test. The WHO confirmed Sunday that existing PCR tests do accurately detect infection from the Omicron variant, but studies are ongoing to determine the effectiveness at recognizing the new strain employed in most test-to-stay schemes.

Since September, there have been over , and in the week before Thanksgiving, children accounted for about a quarter of new infections, according to the American Academy of Pediatrics. Weekly youth cases are on the rise, up 32 percent as of Nov. 18 over the previous week to 142,000, but they are well below their peak in early September of 252,000.

Over 19 million youth have received at least one vaccine dose, President Biden said in his Monday address. Over 99 percent of schools nationwide are now open for in-person learning, he pointed out, compared to less than half this time last year.

The new strain further underscores the importance of continuing efforts to boost vaccination rates within school communities, said Domenech, and raises the stakes for immunizing newly eligible children.

“The bottom line here is that unless we get to the point where the majority of people are vaccinated, where we can get to that herd immunity point, these variants are going to keep coming [and] kids are going to get infected,” he said.

Correction: Last week, 621 schools across 58 districts announced new closures for a variety of reasons. An earlier version of the story incorrectly reported that 9,313 campuses across 916 districts had announced closures last week. Those numbers represent the total closures since the start of the academic year.