Masking will be a key strategy in returning to school safely amid the continued presence of COVID-19 and its delta variant, said a pair of Duke University pediatrics professors who also stressed the importance of enforcing and adhering to mask policies.

Dr. Danny Benjamin, chair of the National Institute of Child Health and Human Development’s Pediatric Trials Network, compared enforcing mask-wearing in schools to giving a child medicine to treat strep throat.

“It will do you no good if you pour it into the child’s mouth and the child promptly spits it out,” he said in a Duke University-hosted media briefing Wednesday on navigating the return to school. “I prescribed amoxicillin, but it’s not going to solve your problem, and the same thing is I think what we are going to see if school districts struggle a little bit with some increased clusters and some secondary transmission.”

Because the delta variant is as contagious as chicken pox, districts are more likely to experience COVID-19 clusters if they have a mask policy in place “but don’t have enforcement and safety plans around that,” Benjamin said.

As case counts rise again and the delta variant continues to spread, educators, students and families across Massachusetts are planning for a new school year with vaccines not yet available for children younger than 12.

In the Bay State, decisions around masking are in the hands of local officials. Last week, the Department of Elementary and Secondary Education issued guidance “strongly” recommending indoor masking for all students in kindergarten through sixth grade and for all unvaccinated students, staff and visitors. State health and education officials recommended that schools allow vaccinated students to remain unmasked.

Dr. Kanecia Obie Zimmerman, a Duke associate professor of pediatrics, said that because COVID-19 shots are not yet available to most students in grades K-8, “it would be wise” to have a universal masking policy for those grades.

“There are nuances, as you get into the older grades, in particular because there is access to vaccines, but as we’ve seen across the country, there are variable rates of vaccination, there are variable rates of community infections,” she said.

Benjamin said mask-wearing provides an “intermediate answer” for preventing COVID-19 transmission in schools until there are high enough vaccination rates among youth.

According to federal data, 260,890 Massachusetts residents between the ages of 12 and 17 — 54.7 percent of that population — were fully vaccinated as of July 30, and 315,301 members of that age group had gotten at least one shot. Among the state’s 18-and-up population, 74.5 percent were fully vaccinated.

Since Friday, when the Baker administration released its school masking guidance, districts have announced varied approaches.

In a note to parents this week, Pittsfield schools Superintendent Joseph Curtis said district officials “will be watching the local data in the coming days and will make a final decision no later than August 23, 2021 as to how our local health and safety practices will be affected.”

Boston officials have said students in the state’s largest school district will be required to wear masks in the fall. Springfield and Amherst-Pelham Regional district officials have also announced plans to require masks.

Billerica is among districts pursuing an age- and vaccination-based approach, with plans to require masks indoors for all students in grades K-6 and for older students, staff and visitors who are not vaccinated. Masks are optional for vaccinated students in grades 7 and above and for vaccinated staff and visitors.

In Arlington, the town’s school district and health department are working with an advisory committee including families, teachers, administrators, community leaders and town officials to develop a school return plan that will outline protocols on masking, distancing, ventilation and other health and safety measures.

Beth Kontos, president of the American Federation of Teachers Massachusetts, sent Gov. Charlie Baker a letter on Wednesday advocating for a universal mask mandate across all grades, calling it “bewildering that your Administration would essentially punt on a matter as pressing and consequential as masking for children under the age of 12.”

“Until the vaccine is available for children under 12, we have an ethical obligation to protect them by mandating the most effective measure at our disposal: universal masking in schools for grades preK-6,” Kontos wrote.

On Sunday, The Massachusetts Teachers Association board voted unanimously to support mandatory mask use in public schools from pre-kindergarten through college, endorsing a statement that calls on Baker to mandate masks in schools and on the Department of Elementary and Secondary Education to issue new guidance that includes universal masking.

In the 200-seat Legislature, Sen. Becca Rausch filed a bill Monday, with four cosponsors, that would require universal masking among students and staff in all K-12 schools and child care programs. That bill has not yet been referred to a committee for review.

Amid the calls for mandates, Baker has defended his administration’s mask advisory, saying that communities should be able to make their own decisions based on local dynamics.

“We strongly recommended that local communities mask kids in grades K through six because there is no vaccination program for kids K through six at this point in time ... strongly recommend is strongly recommend and I fully expect that most communities will do what they think makes the most sense for them,” Baker said Tuesday.