The Biden administration has purchased an additional 200 million doses of Moderna’s coronavirus vaccine, the biotech company announced Wednesday.

Why it matters: Moderna says the additional doses could be used to vaccinate children or — if necessary — as a booster shot.

• Moderna said it plans to deliver 110 million doses in the fourth quarter of 2021 and 90 million in the first quarter of 2022.
• The purchase bumps the total number of Moderna doses ordered by the U.S. to 500 million, 217 million of which have already been delivered.

The big picture: The U.S. and other Group of Seven nations pledged to provide 1 billion doses to help vaccinate people around the world during their summit in the United Kingdom last week.

• The Biden administration has already purchased 500 million Pfizer vaccine doses to share with the world, with the option to buy an additional 200 million.
• It's unclear whether the U.S. will export the new Moderna doses or keep them for booster shots.

What they're saying: “We appreciate the collaboration with the U.S government for these additional doses of the Moderna COVID-19 vaccine, which could be used for primary vaccination, including of children, or possibly as a booster if that becomes necessary to continue to defeat the pandemic,” Moderna CEO Stéphane Bancel said.

• “We remain focused on being proactive as the virus evolves by leveraging the flexibility of our mRNA platform to stay ahead of emerging variants."

Go deeper:Vaccine boosters could be necessary as soon as September