The Biden administration has put Johnson & Johnson (JNJ  ) in charge of the Emergent BioSolutions (EBS  ) facility in Baltimore following a human error that caused 15 million doses of the pharmaceutical giant's COVID-19 vaccine to be ruined. The facility has effectively stopped manufacturing the vaccine developed by AstraZeneca (AZN  ) as a result.

What happened at the Baltimore facility?

About a week ago, Johnson & Johnson announced that its quality control process had detected one batch of ingredients for its single-dose vaccine did not meet its standards at the Emergent facility.

At the time, the facility was working to produce ingredients for both the J&J and AstraZeneca vaccines and had accidently mixed up the separate ingredients for the two, according to The New York Times. The ingredient switch ruined about 15 million J&J vaccines.

None of the J&J doses made by Emergent have been released by the U.S. Food and Drug Administration (FDA) for distribution.

How did the mix-up happen?

The vaccines developed by J&J and AstraZeneca are vector based, meaning they rely on a modified virus--in this case an adenovirus or the virus behind the common cold--to "carry" the COVID-19 spike protein to a human cell to trigger an immune response. This immune response will prepare an individual's immune system to be able to fight off COVID-19 when it encounters the real virus.

At the Emergent facility, the two separate vectors were accidentally mixed-up, with the batch not reaching the fill-and-finish stage of the manufacturing process, according to J&J.

How is the U.S. government getting involved?

The U.S. Department of Health and Human Services (HHS) has placed J&J incharge of the Emergent facility on Saturday, according to senior federal health officials reported by the NYT. Additionally, the HHS has increased Emergent's order by $23 million for the expansion of its manufacturing capacity for the J&J vaccine.

In a statement on Sunday, Emergent said it will align with the Biden administration and halt its manufacturing of the COVID-19 vaccine developed by AstraZeneca as to not have any future mix-ups of approved vaccines as the U.S. continued to accelerate its national vaccination program.

How is J&J getting involved?

J&J stated on Friday that the company is "assuming full responsibility" of the Emergent facility in Baltimore, by adding its own dedicated leaders for operations and quality and by significantly increasing the number of manufacturing, quality and technical operations personnel to work with J&J specialist already employed at Emergent.

The pharmaceutical giant also reiterated that it expects to delivery nealy 100 million single-shot doses of its COVID-19 vaccine to the United States by the end of May. The company will also work closely with the FDA towards the emergency use authorization of the Emergent facility.