The United States will start to share up to 60 million doses of AstraZeneca Plc’s coronavirus vaccine with other countries as they become available, White House senior COVID-19 adviser Andy Slavitt said on Monday.

“U.S. to release 60 million AstraZeneca doses to other countries as they become available,” he wrote on Twitter.

The Associated Press earlier on Monday reported the doses would be shared in coming months following their clearance by the U.S. Food and Drug Administration.

White House Press Secretary Jen Psaki confirmed the move.

The Biden administration in March said it would send roughly 4 million doses of the British drugmaker’s vaccine to Canada and Mexico, and is under growing pressure now to expand sharing of its stockpile with India and other countries.

White House COVID-19 coordinator Jeff Zients told the AP that about 10 million doses of the AstraZeneca vaccine were ready to go and needed to pass a final FDA review, likely in the next several weeks.

He said about 50 million more doses are in “various stages of production” and could ship in May and June.

The United States is looking at options to share the AstraZeneca doses because the vaccine has not yet been authorized for U.S. use by the FDA and will not be needed by states during the next several months, he told the AP.

An AstraZeneca spokeswoman could not comment on specifics of the arrangement, but said the doses were part of its supply commitments to the U.S. government. “Decisions to send U.S. supply to other countries are made by the U.S. government,” she said.

The AP reported that the doses were made at the Emergent BioSolutions facility in Baltimore, which came under harsh criticism for a long list of cleanliness and manufacturing problems found during an FDA inspection.

AstraZeneca is no longer making vaccine at that plant after a batch of Johnson & Johnson’s vaccine was ruined by contamination with ingredients from the AstraZeneca shot.

J&J is now overseeing production of its vaccine at the Emergent plant.