High-risk or elderly residents of the D.C. area who received a Pfizer coronavirus vaccination at least six months ago can receive a booster shot as of Friday, Maryland and D.C. health officials said, although leaders in Virginia have yet to offer their own guidance on the rollout.

Maryland Gov. Larry Hogan (R) called it a “significant step toward providing additional protection for our most vulnerable residents.” Maryland, he noted, had already begun providing booster shots for elderly residents in nursing homes. “While this action was long overdue, I am glad that the federal government has finally approved booster shots for seniors and high-risk individuals,” he said.

The booster shots were recommended this week by the Centers for Disease Control and Prevention for adults 65 and older, front line workers, nursing home residents, and those 50 to 64 with underlying medical conditions — all on the condition that they received their second dose of the Pfizer vaccine more than six months ago.

Health officials say the booster shots will serve as a key safeguard for those populations at greatest risk of severe complications from a breakthrough infection. That is especially true as the highly contagious delta variant continues to drive cases, although numbers appear to be slowing.

An average of 4,625 new daily cases were reported in D.C., Maryland and Virginia since last Friday, down from 5,145 for the previous week. The seven-day average of new deaths in the three jurisdictions was 55 on Friday, which rose from 45 one week ago.

In nearby regions with lower vaccination rates, including the Shenandoah Valley, hospitals are seeing record numbers of coronavirus patients and sending some as far away as Philadelphia for treatment. About 30 percent of people each in D.C., Maryland and Virginia are unvaccinated, according to data tracked by The Washington Post.

In D.C., Mayor Muriel E. Bowser (D) and local health officials encouraged the eligible residents to get their booster shots in a statement on Friday afternoon. The statement noted that individuals can simply self-report that they are eligible and receive the vaccine at any clinic, including city-run sites and pharmacies, to reduce any access barriers.

In Virginia, health officials in Arlington County, Fairfax County and the city of Alexandria said they were not yet administering coronavirus vaccine boosters, as the state had not yet directed them to do so.

But pharmacies, doctors’ offices and privately run clinics would “be in compliance” to administer booster Pfizer shots to eligible individuals, Melissa Gordon, a spokeswoman for the Virginia Department of Health, said in a statement. She said the agency would be “issuing guidance to providers soon to assist in implementing the new recommendations.”

Unlike in the spring, when government officials were distributing the vast majority of coronavirus vaccines at mass sites, many pharmacies and doctors’ offices are now well-equipped to dole out booster shots.

“The key thing that’s different now is that we are not the main game in town,” said Mary Anderson, a spokesperson for Montgomery County’s health department. She said health officials hope that getting a booster shot will look much like getting vaccinated against the flu. In addition to traveling to a county-run clinic in the limited window when it might be open, “you can always walk into a CVS or a Giant pharmacy,” she said.

They appear to be getting close to that goal. After third vaccine doses were greenlighted for some immunocompromised adults earlier this year, only about one in ten eligible Montgomery County residents sought their shot at county facilities, Anderson said. Others who sought third shots — which are separate from booster shots, and have been available for weeks across the D.C. region — went to pharmacies or medical providers instead.

Danny Avula, Virginia’s vaccine coordinator, said in a statement that health officials have been working to prepare for the booster rollout for weeks. He is confident that Virginia will have enough supply, with more vaccination sites being set up. But he noted that his top priority remains increasing vaccination rates in Virginia, given that those who are unvaccinated remain at the highest risk of severe illness and hospitalization.

That reality is playing out in parts of Virginia with lower vaccination rates, including the Shenandoah Valley and Southwest region of the state, where higher hospitalizations are straining resources. Nick Restrepo, the quality and patient safety officer at Valley Health, said the health system this week surpassed its previous high number of coronavirus patients in a day set in January. In a 24-hour period, the system saw 175 coronavirus patients one day this week. The previous high was 167 coronavirus patients.

The Valley Health system operates Winchester Medical Center and Warren Memorial Hospital in Front Royal as well as four smaller rural hospitals in Virginia and West Virginia, where the coronavirus vaccination rates are generally lower than those in Northern Virginia.

On top of coronavirus patients, the hospitals are busy treating people who have delayed care during the pandemic. Moreover, there also tend to be more traumatic injuries in the summer and fall, Restrepo explained. “It’s as bad or worse than it’s ever been,” he said in an interview Thursday. “Overall it’s an extraordinarily challenging time.”

Valley Health this week reinstituted what hospital officials called “crisis measures” first put in place at the height of the pandemic, including limiting visitors and postponing elective surgeries. Winchester Medical Center has had to send patients as far away as Pittsburgh and Philadelphia when the facility is full, and University of Virginia, Inova and Hopkins hospitals are too full to take transfers as they would otherwise.

“Every health system is very challenged right now by the covid cases in Virginia and the number of hospitalizations,” Restrepo said. In the last several weeks, hospitals saw more disruptive behavior from visitors, some of whom refused to follow mask mandates, officials said.

Iyad Sabbagh, chief physician executive at Valley Health, said that while about 85 percent of people admitted with coronavirus infections are unvaccinated, patients will receive the same quality of care regardless of their vaccination status. His statement noted that some patients have not been truthful about whether they are vaccinated because they “fear they will not receive care if they share with staff that they are unvaccinated.”

Michael Brice-Saddler contributed to this report.