WASHINGTON — The Biden administration on Saturday put Johnson & Johnson in charge of a Baltimore manufacturing plant that ruined 15 million doses of the Johnson & Johnson coronavirus vaccine and moved to stop the plant from making another vaccine by AstraZeneca, senior federal health officials said.

The extraordinary move by the Department of Health and Human Services came just days after officials had learned that Emergent BioSolutions, a contract manufacturer that has been making both the Johnson & Johnson and the AstraZeneca vaccines, mixed up ingredients from the two, which led regulators to delay authorization of the plant’s production lines.

By moving the AstraZeneca vaccine out, two senior federal health officials said, the plant can be solely devoted to the Johnson & Johnson vaccine and avoid future mishaps.

The Department of Health and Human Services directed Johnson & Johnson to install a new leadership team to oversee the Emergent Baltimore plant, the officials said. The company said in a statement that it was “assuming full responsibility” for the vaccine made at the facility.

The ingredient mix-up, and Saturday’s move by the administration, is a significant setback for Emergent, a Maryland-based biotech company that has built a profitable business by selling its anthrax vaccines to the Strategic National Stockpile.

A spokesman for Emergent declined to comment, except to say that the company would continue making AstraZeneca doses until it received a contract modification from the federal government.

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The reorganization of the plant is also a setback for AstraZeneca, which, unlike Johnson & Johnson, does not yet have emergency authorization from the Food and Drug Administration for its vaccine. However, one of the federal officials said the government was discussing working with AstraZeneca to adapt its vaccine to combat new coronavirus variants.

AstraZeneca said that it would work with the Biden administration to find a new site to manufacture its vaccine.

So far, none of the Johnson & Johnson doses made by Emergent have been released for distribution. Officials have said it may take weeks to sort out whether other batches were contaminated and for FDA inspectors to determine whether the plant can be cleared to release any doses.