As demand for coronavirus vaccines wanes, public health officials are shifting from not wasting a single dose to not wasting a single arm — even if it means cracking open a multi-dose vial to vaccinate one patient.

The Centers for Disease Control and Prevention on Tuesday advised providers not to miss an opportunity to vaccinate someone who wants the shot — even if that means opening a vial containing many doses without knowing if all of them will be used.

The message prompted public health officials in many states, including Virginia and Maryland, and in D.C. to align with the new guidance and encourage primary-care doctors — who might vaccinate only a few patients at a time — to administer the doses without worrying as much about wastage.

The new approach means providers face a painful choice: puncture a vial containing multiple doses, allowing as many as 10 doses to go to waste, or let a patient walk away unvaccinated.

“It’s going to be a big shift,” said Danny Avula, Virginia’s vaccine coordinator. “I think a lot of providers are going to struggle with that given four months of completely the opposite message. But we’ll continue to reassure them every day.”

The CDC statement Tuesday says more vaccine may be wasted, making doctors uneasy and raising ethical questions as other nations face vaccine shortages.

“It’s why we need to strike the right balance,” Avula said. “We do need to be good global stewards. We do need to think about people across the world.”

Early in the vaccine distribution effort, hospitals and other providers were criticized for failing to quickly administer all their doses, leaving some sitting on shelves, despite overwhelming demand from the public. People stalked pharmacies waiting for leftovers.

Gov. Ralph Northam (D) of Virginia required providers to use their vaccine doses within a week of receiving them. Gov. Larry Hogan (R) of Maryland threatened to withhold vaccines from those who sat on doses.

As supplies increased and eligibility expanded, governments and providers held mass vaccination clinics and accepted walk-ups, boosting the rate of fully vaccinated people to about 40 percent in the greater Washington region.

About two weeks ago, supply outstripped demand, forcing public health officials to rely on doctor’s offices, mobile units and other small sites to vaccinate people who did not want to go out of their way for the shot, are hard to reach or are hesitant.

Virginia officials this past week made policy changes intended to give doctors more flexibility. Under the heading “No Missed Opportunities,” they lifted constraints on when providers had to use supplies, said people could get second doses wherever convenient for them and began to explore ways to distribute small shipments — as little as one vial — around the state.

David Goodfriend, director of the Loudoun County Department of Health, said the original guidance was to have a plan in place to waste zero doses. That has changed.

“We still want them to strive to not miss any doses,” he said, “but if it results in wastage to go ahead and vaccinate someone when they wouldn’t otherwise get it, open the vial.”

Once punctured, multi-dose Moderna vials must be used within 12 hours, Pfizer-BioNTech six hours and Johnson & Johnson two hours, and some have cold storage needs, according to the CDC.

Amy Popovich, nurse manager at Henrico and Richmond City health districts, said that previously, nurses were running vials to different hospital floors before the clock ran out.

“All of us have treated the vaccine like gold over the past few months,” she said.

But Jeff Feit, the community and population health manager at Valley Health, a health-care system based in Winchester, said doctors will still be reluctant to give shots at regular visits, adding the fear of wasting doses on top of logistical challenges.

“I think we need to be cognizant of operational changes we’re asking people to make in the midst of a challenging time with covid,” he said.

Small and solo practitioners have already overhauled procedures multiple times in the past 14 months, and to offer the vaccines they must follow strict storage requirements, gather and report data, seek consent for minors, and make time to give the injections and observe patients for up to 30 minutes.

“It’s going to feel bad if we’re wasting a vial or two every day at a site,” Feit said. “There’s a natural instinct to manage the resource.”

Physicians have advocated for single-dose vials or syringes to reduce the likelihood of waste. Anne Zink, chief medical officer at the Alaska Department of Health and Social Services, said she encountered this dilemma in Hyder, on the U.S.-Canada border in the state, where there were two residents left to vaccinate.

“I had to make the decision, do I open one vial and potentially waste four? Or leave two people stranded there an hour and a half by floatplane away and not get them vaccinated?” she told reporters last week on a call organized by the Association of State and Territorial Health Officials.

Across the nation and locally, wastage rates up until this point have been low — less than one half of one percent compared with an expected wastage rate of 5 percent for other multi-dose vaccines.

In Maryland, 6,435 doses have been wasted and more than 5 million shots were administered as of May 6, said Charlie Gischlar, a spokesman for the state health department. A large chunk of those — 1,580 — were lost when a hospital freezer on the Eastern Shore broke; in other cases there were defective syringes, broken vials, and vaccines thawed and not used, he said.

In Virginia, 5,168 doses were wasted and about 6 million shots were administered as of May 3, according to state health department data.

In the District, 1,587 doses were wasted and 558,319 doses administered as of May 13, a D.C. Health spokeswoman said.

Friday afternoon, Steve Schwartz, a primary-care doctor with a large practice in Montgomery County, Md., was struggling to use the supply he had: 95 Johnson & Johnson doses, set to expire on June 23, and Moderna doses that will be good until November.

Schwartz, who once begged state officials for vaccine doses, hasn’t ordered shots in two weeks. He keeps waitlists and has appealed to family and friends of staff, churches and synagogues, and even the construction site next door. Most have gotten it; others are hesitant.

“Suddenly the demand plummeted,” he said. “We can’t give it away.”

He recently spent 20 minutes gently debunking false claims parroted by a patient who mistrusts the media’s reporting of the pandemic, believing the vaccine would make him sicker than the virus and that cases and deaths were overblown.

“I have a dose for you and I can give to you today,” Schwartz said he told him.

But it was 3:30 in the afternoon and he didn’t have an open vial, so Schwartz took a risk, asking the patient to return the next morning. He did.

It doesn’t always work out that way.

Schwartz’s practice has administered about 2,000 shots and wasted up to 20, he said. Although the numbers are small, Schwartz said they are devastating.

“Knowing this could be helping someone and we’re putting it in the garbage,” he said, “it tears me up.”

The predicament is particularly acute for one of his colleagues, Rajshree Thaker, who has cousins, aunts and uncles in India, where new daily coronavirus cases exceeded 400,000.

She video chats with a cousin on lockdown in India who almost couldn’t get his second shot at a clinic giving 500 doses a day.

At work in her Bethesda office, Thaker recently offered the vaccine to a patient who would have to drive five miles to the practice’s Chevy Chase location where a vial was open.

The patient couldn’t be bothered.

Thaker doesn’t know if she ever got the shot.

Lena H. Sun contributed to this report.