The U.S. has put Johnson and Johnson (J&J) in charge of a plant that ruined 15 million doses of its COVID-19 vaccine and has stopped British drugmaker AstraZeneca from using the facility, a senior health official said on Saturday.

Workers at the Emergent BioSolutions plant in Baltimore several weeks ago mixed ingredients for the J&J and AstraZeneca vaccines, the New York Times reported earlier in the week. J&J said at the time the ruined batch had not advanced to the fill-and-finish stage.

J&J said it was "assuming full responsibility" for the facility, reiterating that it will deliver 100 million doses to the government by the end of May.

The Department of Health and Human Services facilitated the move, the health official said in an email, asking not to be named due to the sensitivity of the matter.

AstraZeneca, whose vaccine has not been approved in the U.S., said it will work with President Joe Biden's administration to find an alternative site to produce its vaccine.

The development further hampers AstraZeneca's efforts in the U.S. The government has criticized the drugmaker for using outdated data in the results of its vaccine trial. It later revised its study.

White House officials did not immediately respond to a request for comment.

The government's move to have the facility make only the J&J single-dose vaccine is meant to avoid future mix-ups, the New York Times said, citing two senior federal health officials.

Top U.S. infectious disease doctor Anthony Fauci said on Thursday the country may not need AstraZeneca's vaccine even if it wins approval.

The U.S. has loan deals to send Mexico and Canada roughly 4 million doses of the AstraZeneca vaccine, made at its U.S. facility.