The global vaccine supply is finally opening up for countries that desperately need the ammo in the fight against the COVID-19 pandemic.

Driving the news: The Biden administration will buy 500 million doses of the Pfizer-BioNTech coronavirus vaccine to share with countries around the world, with the option to buy an additional 200 million.

The news came just a day after the Mastercard Foundation donated $1.3 billion to Africa's COVID-19 response.

• It also comes amid increasingly serious debate over the TRIPS waiver, which would suspend intellectual property protections COVID-19 vaccines.

What we're watching: The administration has already said President Biden will press other rich democracies to share doses.

• The "G7 will vow to deliver at least 1 billion extra doses of vaccines over [the] next year to cover 80% of the world's adult population," according to a draft communique seen by Bloomberg News, their senior White House reporter Jennifer Jacobs tweeted.

But, but, but: There needs to be more investment into readiness to deliver the vaccines.

• "By the end of this year, most countries globally will see distribution, delivery, and demand as the key constraints to vaccination, not supply," Duke's Global Health Institute founding director Krishna Udayakumar told Axios.

What's next: Biden could pursue similar deals with Moderna and Johnson & Johnson.

• "We would be very interested to help ... provide more doses to low-income countries," Moderna CEO Stéphane Bancel said via email. "We are investing to get up to 3B doses in 2022 and we are doing this manufacturing capacity increase to ensure we can help."