Top officials in the District and Maryland announced Thursday that they would embrace CDC guidelines and advise schools that they can operate with three feet of social distance between students in classrooms instead of the previously recommended six feet.

This move would allow schools to accommodate more students in person at a time when demand for in-person learning outstrips the supply of available seats in the region. But how significantly plans for this school year will change is uncertain.

“This updated guidance is the result of numerous and robust academic studies finding that 3 ft of distance between students did not significantly impact transmission of COVID-19 when compared to the earlier 6 ft distancing guidance,” read a letter signed Thursday by Maryland State Superintendent Karen B. Salmon to school leaders across the state.

The District’s traditional public school system said Thursday afternoon that it would adopt the more relaxed social distancing guidelines for the fourth quarter of the academic year, which begins April 19. KIPP DC, the city’s largest charter network, said it is still reviewing the guidance. Friendship, the second largest charter network, said that it would adopt the new guidelines.

In suburban Montgomery County, where students are being gradually phased in for in-school learning through the end of April, the new guidance from the Centers for Disease Control and Prevention did not lead to immediate changes, but school officials said they were exploring the impact of revisions. Neighboring Prince George’s County did not immediately respond to a request for comment, but said last week that no changes were planned.

The guidance is more complicated for middle- and high-schoolers. The D.C. guidance says that these older students should still maintain six feet of social distancing if students are switching classes during the day while there is “substantial community spread.”

D.C. meets the substantial community spread threshold, but the school system has said it will not allow students to switch classes and mix cohorts this academic year. Because students will be in strict cohorts they need to maintain only three feet of social distancing.

The loosening of health guidelines in schools comes as pressure from parents to get their children into a school building before the end of the year is increasing. The District’s public school system is serving around 20 percent of its 52,000 students in person, though thousands of those students are attending school only once or twice a week for a few hours a day.

In D.C., even with the new guidance, it is unclear how many students will get in classrooms for the fourth term. With six feet of social distancing, classrooms are able to fit about a dozen students. Depending on the size and configuration of the classrooms, that could double with just three feet of social distancing.

But the school system still has to juggle staffing and specialized classrooms and has left decisions on adding classrooms up to individual principals. Schools are not required to expand for the fourth term. At a school system town hall Wednesday, an elementary school principal said her school would have minimal expansion for the fourth term, adding one new classroom.

D.C. Schools Chancellor Lewis D. Ferebee has said that the number of in-person seats offered should be driven by family demand, but parents have said their principals have warned them that, because of staffing restraints, they may not be offered in-person slots for the fourth quarter. Seat offers for the fourth quarter are going out early next month, according to the school system.

“They haven’t seen kids in a year, they don’t know who has special needs now. Everyone is seeing attention issues,” said Sarah Swift, a mother of a first-grader who is in an all-virtual class in the Capitol Hill area. “The issues are getting worse as time is going on.”

The loudest calls to more widely reopen schools and loosen health guidelines have come from the city’s wealthiest neighborhoods — where demand is highest for in-person learning. But families are slowly filling up schools that serve low-income populations as well, and some of these schools have wait lists in certain grades.

KIPP DC, whose students mostly live in the city’s lower-income wards, will serve 1,700 of its more than 7,000 students in person four days a week by April 5. The school has 141 who have signed up for in-person learning but are waiting to get their required immunizations before they can enter the school building. There are 111 students on the wait list for in-person learning, and the charter network said it is working to recruit staff to serve these students. The network said it is adding more students to its wait list each day.

At Friendship, 1000 students and 425 staff members will be in person four days a week by March. 29.

“We look forward to the day when 100 percent of students and staff return in person five days a week, and we are planning for the fall with that goal in mind,” said Candice Tolliver Burns, Friendship’s chief communications officer.

The District’s new health guidance also requires the school system and every private and parochial school to submit a plan to the superintendent’s office detailing how they will reopen schools while adhering to health guidance.

D.C. leaders have said that extracurricular activities, including drama, athletics and band, can resume with health restrictions in place.

Officials also announced this month that any school staff employee working virtually is eligible for a vaccine. This week, the city set aside more than 3,500 vaccine doses for teachers, health-care workers and senior citizens, in addition to the weekly allotments for essential workers and senior citizens.

Staff members working in person in school buildings have already had the opportunity to be vaccinated.