The White House, worried that coronavirus vaccination rates among young people are lagging behind as the new school year approaches, unveiled Thursday a new push to get students their shots, including enlisting pediatricians to incorporate vaccination into back-to-school sports physicals and encouraging schools to host their own vaccination clinics.

The initiative, announced by Education Secretary Miguel Cardona, comes as the school year is beginning in many parts of the country. It will include a “week of action” starting Saturday, with text chains and phone banks aimed at encouraging vaccination.

Experts and school superintendents said in interviews that increasing vaccination among students may be a slow, uphill battle.

The Pfizer-BioNTech vaccine was authorized for people ages 12 and older in May, but young people remain far less likely than older adults to have gotten their shots. Although the nation passed President Joe Biden’s goal of having at least 70% of adults at least partially vaccinated, only 40.2% of 12- to 15-year-olds and 50.6% of 16- and 17-year-olds have received at least one dose, according to the Centers for Disease Control and Prevention.

Last week, the CDC said it wanted in-person schooling to resume across the country, and it updated its mask guidance to call for universal mask use by students, staff and visitors in schools, regardless of their vaccination status or the rate of community transmission of the virus.

“Children should return to full-time, in-person learning in the fall, with proper prevention strategies in place,” Dr. Rochelle Walensky, director of the CDC, said at a news briefing.

A White House official, speaking on condition of anonymity to preview Cardona’s announcement, said the administration is focusing on school athletics as an important path to vaccination. Millions of American students play organized sports, and some school officials are making the case that if student athletes get vaccinated, they will be able to avoid quarantining — and forfeiting their games — if they are exposed to an infected person.

To that end, the White House official said, the administration has enlisted the help of various groups, including the American Academy of Pediatrics and the American Medical Society for Sports Medicine, to put out guidance for doctors and to update the forms required for school physicals.

Cardona and Doug Emhoff, husband of Vice President Kamala Harris, are expected to visit a school vaccination clinic in Kansas next week.

In remarks to the nation last week, Biden called for every school district in the country to host at least one pop-up vaccination clinic, and many schools and school districts are already doing so. The COVID Collaborative, a bipartisan group of politicians and policymakers, has also been working with the White House to promote school-based clinics.

But some school officials are finding that persuading parents to get their students vaccinated is a difficult task.

The school district in Anchorage, Alaska, has been a national leader in encouraging vaccination; a clinic it hosted last year at the district headquarters drew 29,000 people between January and April, many of them older adults eager for their shots, Superintendent Deena Bishop said in an interview. But when Anchorage set up clinics in schools, the demand was much lower; those clinics vaccinated only about 30 students a day, Bishop said.

Other superintendents said school-based vaccine clinics, which typically partner with pharmacies or county health departments, may be a hard sell in areas where there is already resistance to vaccination.

“For people who are for it, it’s an easy one; they support vaccination as a strong strategy to fight COVID, and they don’t see any issue with the use of public space,” said Kristi Wilson, superintendent of Buckeye Elementary School District, just outside Phoenix, who recently completed a term as president of AASA: The School Superintendents Association, which represents 13,000 school superintendents across the country.

“But the other side I’m hearing is that, ‘Where do you draw the line? Who’s going to administer it? Even if public health does it, is it an appropriate use of space?’ If you have a community that is very anti-vaccination, how do you manage that?” she said.

This latest Biden administration initiative to address the pandemic comes as coronavirus hospitalizations are surging again as the more contagious delta variant rages across the country.

The number of people now in the hospital in the U.S. with COVID-19 has almost quadrupled over the past month to nearly 45,000, turning the clock back to early March, according to the Centers for Disease Control and Prevention.

That’s still nowhere close to the nearly 124,000 people who were in the hospital at the very peak of the winter surge in January. But health experts say this wave is perhaps more worrying because it has risen more swiftly than prior ones.

The Associated Press contributed.