Johnson & Johnson has backed off a previous pledge to deliver 24 million additional doses of its one-shot vaccine by the end of April amid the continued failure of its troubled contract manufacturer in Baltimore to win government manufacturing certification.

With domestic production of the company’s vaccine still unapproved, the government slashed its national allocation of the J&J vaccine to states by 86 percent to just 700,000 doses next week, down from nearly 5 million, a cut that Maryland Gov. Larry Hogan (R) called “very concerning.”

The cuts will make it harder across the country for much of April to find the Johnson & Johnson shot, which some people favor because it requires only one trip to a clinic or vaccination site. The hashtag #OneAndDone has become popular among people receiving it.

The new single-shot J&J vaccine doesn't need subzero storage, and could help harder-to-reach communities get access to coronavirus protection. (Joshua Carroll/The Washington Post)

D.C. is in line to receive just 1,300 doses of the company’s vaccine next week, down from 10,800 this week, according to the data tracked by the Centers for Disease Control and Prevention. California will receive 67,000, down from 572,000.

The Biden administration put Johnson & Johnson in control of manufacturing at the Emergent BioSolutions plant in Baltimore last week after 15 million doses of its vaccine were contaminated by another vaccine being made at the plant by AstraZeneca.

Administration officials suggested the problems in ramping up, mostly due to the lack of manufacturing certification at the plant, should be resolved in a matter of weeks.

The rollout of Johnson & Johnson shots, authorized by the Food and Drug Administration in February, has been so slow that it is not yet a significant factor in the U.S. vaccination surge, which has been fueled by the Pfizer-BioNTech and Moderna two-shot vaccines.

Only 5 million Johnson & Johnson shots have been administered, according to CDC data, compared with 170 million shots of the other two vaccines.

“Johnson & Johnson expects a relatively low level of weekly dose delivery until the company secures FDA authorization,” White House coronavirus response coordinator Jeff Zients said Friday at a media briefing. “With FDA authorization, the company expects a cadence of up to 8 million weekly doses total across state and federal channels later in April.”

The company and government have not said when that clearance is expected.

State officials in Maryland were preparing for a longer wait than Zients outlined. Hogan said Friday that White House officials notified him the reduction will extend for three weeks, which cumulatively reduces Maryland’s expected Johnson & Johnson allotment by more than a quarter-million doses. Next week’s allotment will be 10,500 for Maryland, a reduction from 88,800 this week, the CDC projected.

“It’s very frustrating,” Hogan said during a news conference, adding that the administration said the doses will be delivered later in May, rather than this month.

“The last thing we wanted to hear about was we were getting less vaccine,” Hogan said. “We had wanted to continue to ramp up, as they had been promising. … We were hoping, with the infrastructure that we built, that we were going to be able to finish a huge chunk of this in April and May, and now it’s going to be a little slower in April.”

Virginia’s allocation will go from 124,700 this week to 14,800 next week, according to the CDC. The drop in supply will not affect the state’s goal to begin vaccinating people 16 and older by April 18, officials said. But it will affect the pace of those vaccinations when they start happening and may mean that college students who were preparing to receive their doses next week will have to wait another week.

“Everyone who wants to be vaccinated will have a chance to do that by the end of May, at least for a first dose,” Danny Avula, the state’s vaccine coordinator, said in a news conference, adding that the state expects its weekly Johnson & Johnson supply to reach its previous levels by the end of April.

Johnson & Johnson and President Biden’s team have said that the company met its obligations to produce 20 million doses of its vaccine by the end of March. It met that goal with a delivery of 11 million doses last week. The company has imported doses from overseas while the Emergent plant remains unapproved. Domestic capacity will increase further later this year when a partnership with Merck for production at Merck factories bears fruit.

“I do think that the company is doing everything they can,” Zients said at the Friday briefing. “They now have complete responsibility for that whole facility. They have their best people at that plant, and they are partnering with Merck, who has expertise.”

The last time Johnson & Johnson publicly pledged to produce an additional 24 million doses this month was on March 31. Since then, the company in public statements has said only that it will meet a target of 100 million doses delivered by the end of May.

Johnson & Johnson has an unknown volume of doses prepared and ready to distribute once the Emergent plant does win certification.

“The company continues to work closely with the U.S. Food and Drug Administration toward” manufacturing certification at Emergent’s Baltimore facility, Johnson & Johnson spokesman Jake Sargent said in an email Friday. “The Company expects to deliver nearly 100 million single-shot doses of its coronavirus vaccine to the U.S. Government by the end of May.”

The CDC also said it was evaluating reports in Colorado, Georgia and North Carolina of people feeling faint after receiving the Johnson & Johnson vaccine. Officials in those states temporarily closed vaccination sites after apparent severe side effects associated with the shots. Heat at a Georgia fairgrounds site may have been a factor, according to local reports.

“CDC is aware of several incidents of vaccine recipients experiencing dizziness, lightheadedness, feeling faint, rapid breathing, and sweating (vasovagal or anxiety-related) symptoms following covid-19 vaccines in Iowa, Colorado, Georgia, and North Carolina,” the agency said Friday. “CDC has performed vaccine lot analyses and has not found any reason for concern. Currently CDC and FDA are not recommending health departments stop administering any lots of covid-19 vaccine.”

“Covid-19 vaccines are safe and effective,” the CDC added. “Many people don’t have any side effects after coronavirus vaccines, but some people will have pain or swelling at the injection site or fever, chills, or a headache. These typically don’t last long and are signs that your body is building protection.”

Johnson & Johnson said it was examining the reports and sharing information with the FDA, a routine part of side-effect reporting for companies.

Separately, an official from the European Medicines Agency said at a news conference this week that it was aware of three cases of blood clots among people in Europe who received the Johnson & Johnson vaccine but that no definitive link has been established. The agency said the benefits of getting vaccinated far outweigh any potential blood-clot risks. Johnson & Johnson said it was closely tracking the cases.

“At present, no clear causal relationship has been established between these rare events and the [Johnson & Johnson] coronavirus vaccine,” the company said. “We continue to work closely with experts and regulators to assess the data and support the open communication of this information to health care professionals and the public to help ensure that, in the event of a very rare illness, appropriate steps can be taken for quick diagnosis and treatment.”

Extremely rare cases of blood clots have been “plausibly” linked to AstraZeneca vaccine by the European Medicines Agency. That vaccine, which is based on a similar technology to that of the Johnson & Johnson vaccine, has not yet been approved in the United States.

Erin Cox and Antonio Olivo contributed to this report.