With the vast majority of U.S. students once again learning in classrooms, 180 of the largest 500 U.S. school districts have enacted requirements for their staff to be vaccinated against COVID-19, according to an analysis published Monday by Burbio, an organization that has tracked school safety policies through the pandemic.

It’s a safety measure that health experts say represents a key step toward improved coronavirus safety in school — especially as younger students remain ineligible for shots likely until November. Although children rarely fall seriously ill from the virus, young people still make up of new cases in the U.S. and school-based outbreaks have triggered some already in 2021-22.

“Most pediatricians that I’ve spoken with … absolutely support vaccine mandates for teachers,” Kristina Deeter, professor of pediatric medicine at University of Nevada, Reno School of Medicine, told ����Ӱ��. “It’s the right thing to do.”

In 11 states, coronavirus vaccines are mandated for teachers statewide, the University of Washington’s Center on Reinventing Public Education reports, meaning a considerable share of the 180 districts with staff mandates enacted such policies because state law required it.

Still, vaccination rules , with some mandates having already kicked in and others not taking effect until next month.

Some school systems have more lenient policies, such as Philadelphia, which acknowledged that unvaccinated teachers , though they will be subject to twice-weekly testing. Others impose stricter sanctions, like New York City, which is barring unvaccinated teachers from entering school buildings and putting them on unpaid leave until they get the shot.

Even those districts where staff have a choice between vaccination or regular testing are included in the 36 percent tally, Burbio co-founder Dennis Roche confirmed to ����Ӱ��.

The New York City mandate, which took effect Oct. 4 after a brief legal challenge, applies to roughly 150,000 people who work in the nation’s largest school system, and of employees to receive their shots in the weeks before the rule took effect. Some 96 percent of teachers in the district have now been immunized against COVID-19, The New York Times reported.

By contrast, Los Angeles, the country’s second-largest school system, on Monday extended its deadline for employees to receive their shots from Oct. 15 to Nov. 15, fearing that strict enforcement would . Unlike the New York City mandate, the L.A. rule requires two doses before the deadline for educators receiving the Moderna or Pfizer vaccine.

While many teacher mandates are in deep blue states, the San Antonio Independent School District has an immunization requirement set to go into effect Oct. 15. Earlier this month, the district’s rule from Texas Attorney General Ken Paxton when a county judge denied the state’s motion to secure a temporary injunction on the mandate. A ruling on the policy from a higher court is .

Meanwhile, on Monday, Texas Gov. Greg Abbott issued an executive order banning all COVID-19 vaccine mandates in the state, .

“We are reviewing the new executive order and consulting with our legal counsel and Board of Trustees to determine how the district will proceed with its employee vaccine mandate,” a San Antonio ISD spokesperson wrote in an email to ����Ӱ��.

In lieu of mandates, other Texas districts are providing cash incentives for teachers who roll up their sleeves. , and each deliver $500 bonuses to fully vaccinated educators.

Vaccine mandates for students remain much more rare, with only a select few districts having implemented such rules. California districts Los Angeles, Oakland and Culver City as well as Hoboken, New Jersey have each made immunization a requirement for in-person school for vaccine-eligible students, with deadlines in the coming months. Washington, D.C. is .

In early October, California Gov. Gavin Newsom announced that coronavirus vaccines will be required for all eligible students in the state, though the rule will .

Burbio’s count that 36 percent of top districts require teachers to be immunized comes as the rush to embrace such policies has slowed considerably. After eight states moved to enact educator mandates in late August and early September, only one — Delaware — has added a similar rule since then, CRPE reports.

But even as COVID case counts , Deeter, the pediatrics professor, warns that now is not time for the country to let down its guard.

“As the surge goes down … now everybody’s like ‘Yay! [The pandemic] is over.’ It’s not over. It’s not even close to over. We are just prepping for the next wave,” she said. “We have to prepare.”

And then came the Delta variant.

Pediatric coronavirus cases have now surged above 250,000 for the first time since the start of the pandemic, according to . Hospitalizations of children stricken by the highly transmissible strain are reaching and some of students across the country last week were quarantining away from schools that had just barely begun. With a swiftness that surprised even health experts, the virus has across some 278 districts in 35 states, according to the website Burbio, a data service that tracks school calendars.

As for the adults in schools, at least have died of the virus since mid-August and shut down all its schools earlier this month after two teachers perished in the same week.

The Delta drumbeat of distress is one of the main reasons that President Joe Biden came out Thursday with a new plan of attack, including mandatory vaccinations for some 300,000 school staff members working for federal programs, such as Head Start or schools operated by the Bureau of Indian Education, and grants for districts confronting loss of funding for implementing mask mandates.

It will take some time to tell if Biden’s new strategy will be successful in beating back this latest surge. Right now, many parents and school officials are in a state of anxiety about how to keep their K-12 communities safe and perhaps questioning whether they miscalculated the strength of the COVID-19 enemy.

Complicating the matter further, decisions to implement basic virus mitigation measures in school have in some cases exploded into or even .

Amid the uncertainty and high tensions, and with , ����Ӱ�� spoke directly to health experts for clarity on how to understand the virus in this critical stage and tips on how to safely navigate the back-to-school season.

Here’s what they had to say:

1 We’ve seen a surge in pediatric coronavirus cases. Should we abandon the prior wisdom that kids rarely catch COVID, and when they do, it’s not too serious?

Not exactly.

“[The Delta variant] is more infectious, but it’s not a whole new game,” explained Benjamin Linas, professor of medicine at Boston University.

The variant’s high transmissibility has pushed up case counts, including among children, he told ����Ӱ��. But serious illness among young people remains “vanishingly rare,” he said — citing a case fatality rate of .00003 for those under 20.

“This underlying reality that kids are at far less risk of severe COVID-19 than adults remains true, even with Delta.”

Young people do represent a larger share of infections nationwide now than they did at the outset of the pandemic. But that’s likely because far fewer minors than adults are vaccinated, and many remain ineligible for shots, said Kristina Deeter, professor of pediatric medicine at University of Nevada, Reno School of Medicine.

In most cases, “[kids] are not as sick as the adults,” she agreed.

Still, Rebecca Wurtz, professor of health policy at the University of Minnesota, cautions that the risk of infection remains high, particularly for the unvaccinated. The idea that young people couldn’t catch or spread COVID was always silly, she told ����Ӱ��, and the Delta variant means that transmission is now easier than ever before.

“Delta will find you if you are not thoughtfully masking and social distancing,” she said.

2 Does the Delta variant make kids sicker than previous strains?

There is no conclusive evidence that it does, according to the experts.

“The jury’s still out,” said Deeter.

Studies from Canada and Scotland have found that than those infected with previous mutations of the virus.

And while those papers don’t examine virulence specifically among young people, Wurtz believes it could still be “reasonable to extrapolate that to kids.”

Evidence from the U.S., however, seems to contradict the idea that Delta causes more severe infections among youth. Even as pediatric COVID cases have surged, the proportion of children and adolescents hospitalized with severe disease has , points out Amruta Padhye, pediatric infectious disease specialist at the University of Missouri.

The hospitalization rate among unvaccinated adolescents was , recent CDC data reveal.

3 After the Pfizer vaccine’s full approval from the FDA, parents may now theoretically seek “off-label” vaccines for children under 12. Should they do so?

In short, no.

Although the FDA’s full approval of the Pfizer vaccine for those 16 and up means that doctors now have the power to prescribe the shot “” to any individual regardless of age, it would be irresponsible to do so, said Deeter.

The biggest unknown, she explained, is dosage. She prescribes drugs off label every day as a pediatrician, but explained that the COVID vaccine is different because it’s still so new.

“I don’t feel safe even deciding on what dose I might want to prescribe for a child. I have no idea what’s going to work,” she said, explaining that too much vaccine could elevate risks such as myocarditis, already more prevalent in young vaccine recipients than adults, and too little vaccine might not provide adequate protection against the coronavirus.

“There’s a reason that we have the approval process, even in the middle of a crisis,” added Linas. “I don’t recommend going out to get your child vaccinated before the vaccine has actually been approved or emergency authorized for kids.”

Youngsters aged 5 to 11 are expected to become eligible for coronavirus shots , experts say. The process has stretched out over months in part due to federal health regulators efforts to bolster confidence in the shots by in clinical trials.

Once shots are approved for that age group, they will be the most effective way to keep children healthy, said Linas.

“With the vaccine, you’re very well protected from the bad outcomes.”

4 Should schools implement vaccine mandates for staff?

Immunization requirements for school staff have multiplied since the FDA issued full approval for the Pfizer vaccine. ​, , and multiple other states have enacted rules requiring educators to receive the COVID shot or be regularly tested for the virus.

In his Thursday address, which unveiled new vaccination rules covering two-thirds of all U.S. workers, President Biden to help move the needle on teacher immunization from its reported 90 percent level up to 100 percent.

“Vaccination requirements in schools are nothing new,” said the president.

Expecting teachers to be immunized against COVID represents a sound public health policy, says Linas.

“It’s reasonable for school districts … to say to their educators and staff… ‘We have an expectation that if you’re going to come into our buildings where we have our unvaccinated children, we expect you to be vaccinated. And if you won’t do that, then I’m sorry, you can’t teach.’”

That strategy also minimizes learning disruptions, pointed out Janet Englund, professor of pediatrics at the University of Washington School of Medicine.

“When a teacher gets sick, he or she is unable to perform his or her job,” she told ����Ӱ��.

5 What about vaccine mandates for students?

Very few school districts have extended vaccine mandates to students, as 12- to 15-year-olds remain eligible for shots only on an emergency authorization basis, and those under 12 are still ineligible.

On Thursday, however, Los Angeles Unified School District, which serves 600,000 students, became the first major U.S. school district to require that eligible students attending school in person be fully vaccinated against the coronavirus. Students 12 and older in the nation’s second-largest school system will have to receive their second dose of the shot by Dec. 19, officials announced.

Culver City, California and also instituted similar requirements for students in late August. Experts told ����Ӱ�� that they expect the vaccination rules to face legal challenges.

Although Englund said she is a believer in many student vaccine mandates — they helped control diseases such as measles and polio, she pointed out — requiring a vaccine that is approved only on an emergency use authorization may be premature.

“It’s not quite time,” she said.

Dr. Anthony Fauci, however, expressed his while speaking on CNN in late August, and the University of Minnesota’s Wurtz told ����Ӱ�� that she is “absolutely in favor of mandatory vaccinations for students,” due to the high safety and efficacy of COVID shots.

6 How effective are masks and other safety mitigation measures at slowing the spread of COVID in school?

Experts agree that safety measures to slow the spread of COVID are more effective when implemented in tandem with multiple others than on their own.

“[Masking] has to be a part of a layered protection strategy,” UCLA professor of pediatrics Ishminder Kaur told ����Ӱ��.

That means that classrooms should employ all strategies available to them, she said: universal masking, ventilation, distancing, outdoor activities and rigorous testing to keep infected students out of the classroom.

Doing so can result in schools effectively containing the virus and keeping case rates below those of surrounding communities, academic studies show.

Although quarantining students exposed to the virus can disrupt academics, experts said it is a necessary step to contain transmission. They pointed out that with widespread access to testing, a negative result after five days may allow students to return to the classroom more quickly. On Thursday, Biden announced that the White House will move to make 280 million rapid and at-home tests available using the Defense Production Act and lower the cost of over-the-counter tests from Walmart, Kroger and Amazon.

Some districts’ quarantine protocols are more stringent than those recommended by the CDC, according to a recent survey of 100 districts from the University of Washington’s Center for Reinventing Public Education.

Some observers have recently made the case that the , but Kaur points out that a recent study from Bangladesh with a randomized design — considered the “gold standard” in causal research — finds that , though it cautions that cloth masks may be less effective.

And while masking controversy has turned many school board meetings ugly, including in Broward County, Florida where the board chair said “all hell broke loose” when they required face coverings in defiance of Gov. Ron DeSantis’s order, kids don’t actually seem to mind wearing masks, said Kaur.

“They’re not fidgeting, they’re not touching it,” she said of the youngsters who come into her clinic. “It’s the new normal for them.”

Deeter, who works in a sedation clinic and has to ask kids to remove their masks, has observed the same.

“They get so upset when I try to take it off of them. It’s their buddy,” she said.

7 Outside of school, what’s the best way to navigate playdates and other social activities?

The number one tip, experts say, is to stay outside as much as possible.

“Outdoor activities were not the ones that were spreading these infections, which remains true even for Delta,” said Kaur, although she recommended avoiding overcrowded locations even outside. For example, coaches calling players into a huddle might ask everyone to momentarily mask up.

Even when the weather gets cold, Wurtz recommends limiting indoor hangouts. She suggests some compromises: building a snowman outside then coming indoors for hot chocolate at the end, perhaps.

8 What’s the COVID end-game for schools?

Once all students have had the opportunity to receive COVID vaccinations, it could be time to consider rolling back virus mitigation protocols, Linas said, and beginning the conversation about how to live with a virus that within the global population. But that’s still a long way out.

“We’re not there yet,” he said.