Elementary, middle and high schools in the U.S. are opening this month, allowing students to fully attend in person as the country struggles to get back to normal. But open schools have put many parents in an agonizing position. Pediatric hospitalizations for COVID have reached all-time highs in some regions, several governors have banned public school mask mandates, and no vaccines are yet available for children under age 12. And all eyes are on how the march of the Delta variant across the country might affect child safety and disrupt back-to-school plans.

To chart a course through these uncertainties, Scientific American asked experts in childhood infectious disease and in epidemiology what a good scenario for returning to school looks like. Physicians and scientists also offered strategies for what parents can do when their choices are limited and difficult. Here is what the experts said.

With masks, low-risk in-person schooling is possible.

Dean Blumberg, chief of pediatric infectious diseases at the University of California, Davis, Children’s Hospital, says that even before vaccines were available, masking mandates in schools worked quite well. During the 2020–2021 school year (before Delta was circulating widely), where school mask mandates were in place, viral transmission was limited. A report on North Carolina schools earlier this year identified only 363 cases of in-school transmission among more than one million students and staff at 100 school districts and 14 charter schools where masking was the norm. What is key is that “children can follow the masking guidance,” Blumberg says, noting that evidence suggests that more than 90 percent of school children do so.

In-person schooling is important, says Sara Bode, medical director of school health services at Nationwide Children’s Hospital in Columbus, Ohio, and incoming chair of the American Academy of Pediatrics’ Council on School Health Executive Committee. Virtual classes might lower chances of viral exposure. But there are other risks associated with remote learning, she says, and they include “significant academic losses, along with social and emotional struggles.”

Bode agrees with Blumberg that the evidence supports the idea that children can adhere to masking and that the practice strongly reduced infections in the pre-Delta era. To work properly, Bode says, a mask should cover the nose mouth and bottom of the chin with no gaping. And it is important for the covering to be comfortable for a child. “The mask that they’re wearing consistently is the best choice of mask,” she says.

Schools that do not require masks put students at greater health risk.

Schools without mask mandates subject children not only to a higher risk of viral transmission but also to the experience of seesawing between virtual and in-person classes as outbreaks lead to school closures, followed by reopenings. Some districts are weakening mandates and turning them into vaguer recommendations. Bode says such moves are “taking away a safety measure that we know worked, and that’s a recipe to definitely go back to all-virtual learning, back and forth, and that is detrimental to [children’s] mental health.”

Masks are expected to work against Delta, but experts are watching the variant closely.

The Delta variant has a higher rate of infectiousness than other versions of the coronavirus, and some studies have found that patients infected with it were more likely to be hospitalized than patients infected with previous variants. Just how these features will affect mitigation measures for children is still not known, says Katelyn Jetelina, an assistant professor of epidemiology at the University of Texas Health Science Center at Houston. “But I am pretty confident that if public health mitigation measures aren’t implemented, we will see substantial spread in schools,” she says. “This isn’t close to being done for kids.”

Vaccinations and ventilation are extremely important.

Schools “need to double down on mitigation efforts in the face of Delta,” Blumberg says. That means making sure that “everybody who is eligible to be vaccinated is vaccinated,” including students age 12 and older and adults who work at the facilities.

“The most powerful tool we have now is vaccination, and those students 12 and up who can be should be vaccinated,” says Georges Benjamin, executive director of the American Public Health Association.

Unfortunately, even students who are eligible are not being vaccinated at very high rates, Jetelina notes. For students under age 12, “we’ll be lucky to have vaccines in arms by December,” she says. Low uptake among eligible students can compound risk for the younger ones. And a mix of vaccinated and unvaccinated students is yet another reason schools should have blanket mask mandates. Implementing policies across all ages “is just cleaner,” Jetelina says.

Another key safety measure is ventilation and air filtration. Benjamin says that in the past year, federal money was distributed to some older public schools to update their airflow systems. That is important, Jetelina says, and good ventilation, including from open doors and windows, is “highly effective in reducing spread.” The U.S. Centers for Disease Control and Prevention advises that HVAC (heating, ventilation and air conditioning) systems should be set to bring in as much outdoor air as possible and should have highly effective filters. Physical space among students is not as important as these other factors, experts say, based on evidence suggesting that with masking in place, there is no difference in transmission between three and six feet of distancing among them.

Adults can set an example by masking up, too.

Because it is currently difficult to monitor everyone’s vaccine status in the U.S., masking across all ages in schools is the best way to ensure reduced disease spread, Bode says. “We are not at a place that we can confidently say that no one has to mask” even in vaccine-eligible student populations, she says.

Another reason to employ universal masking regardless of vaccine status is to normalize mask wearing for younger children. Role models are important, Blumberg says. “It’s nice if authority figures or teachers are masking, too” he says.

Parents may need to take the lead, responding to local conditions and politics.

Local factors will affect the risk-benefit balance for a child attending school. Jetelina says that two metrics require attention at the county level: the daily number of COVID cases per 100,000 people and the local percentage of tests that are positive for the novel coronavirus. When these figures start to climb, the risk climbs, too. Parents can consult with local public health agencies—many of which maintain Web sites with this information—to determine what the numbers mean for risks in local schools.

To make matters more difficult, some states are opposing masks and other disease-control measures. In Texas, for example, Governor Greg Abbott—who himself recently tested positive for COVID—has banned public schools from establishing mask or vaccine mandates. In Florida, Governor Ron DeSantis has done the same. In both states, disease case counts and positive COVID test results are skyrocketing in several places.

Experts chafe at these obstacles. “School districts should be allowed to decide for themselves whether they’re going to have that policy” of requiring masks, based on local conditions that are determined by county public health departments, Blumberg says.

Benjamin agrees. When asked about the Texas Education Agency’s recently publicized policy that administrators do not need to notify parents about a COVID case in their school, he says that “inhibiting the ability of a school to share that information with parents is not good medical practice or good public health practice.” When parents are unable to find out about health conditions at a school, Benjamin says, that is yet another reason to ensure their children wear a mask.

Adults can work to prevent bullying over masks.

Without clear health standards such as mask mandates, Benjamin says, there can be a “toxic environment where you have bullying and stigmatization because a child is wearing a mask. We scar these children for life when we put them in these kinds of terrible situations.”

Adults must make efforts to keep this type of activity and toxicity low. “Teachers are going to have to be sensitive to the needs of those children,” Benjamin says. Jetelina says that parents may have to take on the extra burden of advocating for safety measures to their local and state leaders. Where mandates are lacking, concerned adults may need to implement volunteer testing or work with the school to frame mask wearing as a positive choice. “Even though they can’t mandate it, [schools] can strongly recommend it,” she says.

Missing masks can make inequality in education worse.

Bode is concerned that when outbreaks shut schools because of poor safety measures, the closures will exacerbate educational disparities between poorer and wealthier communities. A stark example is from the first year of the pandemic, when many public school districts in large cities did not return to in-person learning as rapidly as some of their private school counterparts. “Community support for putting safety measures in place is important to ensure that every public school district offers kids the same opportunities,” Bode says. Where mask mandates do not exist, parents have to turn to “grassroots community pressure,” she adds. And where parents lack the time and resources for such efforts, disparity gaps with wealthier communities may widen.

Still, without the widespread use of measures such as mask mandates and vaccination requirements, she says, the path to the end of the pandemic will remain elusive. Blumberg agrees. “We’ve got all these tools in the toolbox to control this pandemic,” he says, “and it makes no sense to start throwing away tools when you need them most.”