The Biden administration announced today that it will begin sharing its store of AstraZeneca’s COVID-19 vaccine following safety reviews.

Once the vaccine clears federal safety reviews, 60 million doses of the vaccine are expected to be made available, according to a Tweet from senior White House advisor Andy Slavitt.

“BREAKING: U.S. to release 60 million Astra Zeneca doses to other countries as they become available,” Slavitt wrote on the social media platform.

He followed the initial announcement with a reply, saying “to everyone who understandably says: ‘about time’ or ‘what were they waiting for’, at this time there are still very few available. No real time has been lost.”

The Associated Press, which was first to report the news, said the decision expands upon Biden’s earlier promise to share 4 million doses of the vaccine with Mexico and Canada.

According to the AP report, the White House is confident in the supply of the approved vaccines currently being administered in the U.S. — Moderna, Pfizer and once again Johnson & Johnson following the restart of use of the vaccine after a two-week pause. AstraZeneca’s vaccine is not yet approved in the U.S., but is being used in several countries around the world.

London-based AstraZeneca faced scrutiny similar to Johnson & Johnson’s after reports of blood clots, with several European countries suspending the use of the vaccine before the European Medicines Agency determined last week that the benefits of the vaccine outweigh the risks.

AP said 10 million AstraZeneca vaccine doses have been produced but haven’t passed review by the FDA, although that could happen in the coming weeks. Another 50 million doses or so are in production and may be available to ship in the coming months, should the FDA authorize it. AstraZeneca is contracted with the U.S. government for 300 million doses.

There is no certainty over where the doses will be delivered, as AP reported that both Mexico and Canada have requested more doses from the Biden administration and several other countries are also seeking aid in the form of vaccines.

“Given the strong portfolio of vaccines that the U.S. already has and that have been authorized by the FDA, and given that the AstraZeneca vaccine is not authorized for use in the U.S., we do not need to use the AstraZeneca vaccine here during the next several months,” White House COVID-19 coordinator Jeff Zients said, according to the AP report.. “Therefore the U.S. is looking at options to share the AstraZeneca doses with other countries as they become available.”