The United States is reportedly planning to purchase 500 million doses of the Covid-19 vaccine manufactured by Pfizer-BioNTech to donate to low- and middle-income countries around the world, and federal officials are reportedly in talks with Moderna to secure additional vaccine doses to donate.

Your top resources on the Covid-19 vaccines

US securing doses from Pfizer and Moderna

According to people familiar with the plan, who spoke to the Washington Post on condition of anonymity because the deal has not yet been made public, the first 200 million doses of Pfizer vaccines will be distributed this year, while the remaining 300 million will be doled out in the first half of 2022.

Radio Advisory episode: Vaccinating the globe, the ultimate systemness challenge

The doses will be purchased at a "not-for-profit" price, the sources told the Post.

All vaccines will be distributed through COVAX, the initiative supported by the World Health Organization to share vaccine doses with countries in need. The doses donated by the United States will be directed to low- and middle-income countries, the Post reports. In total, COVAX aims to deliver two billion doses of Covid-19 vaccines around the world by the end of 2021, with a goal of vaccinating 20% of the populations of countries in need.

Jake Sullivan, national security advisor for President Joe Biden, would not elaborate on the White House's plans to secure vaccines for donation, saying that Biden would make an announcement Thursday at the Group of Seven summit in the United Kingdom.

The United States is also in talks with Moderna to secure more vaccine doses to donate to countries in need, a person familiar with the talks told CNBC. The person said the discussions could potentially lead to a deal similar to the one with Pfizer.

A spokesperson for Moderna told Bloomberg the company is interested in partnering with the U.S. government to provide vaccine doses for low- and middle-income countries but would not provide any details about specific discussions.

Last week, the Biden administration announced it would donate 25 million doses of vaccines made by Pfizer and Johnson & Johnson to countries around the world through COVAX.

In a statement, Jeffrey Zients, the White House official in charge of developing a global vaccination strategy, said President Biden will "rally the world's democracies around solving this crisis globally, with America leading the way to create the arsenal of vaccines that will be critical in our global fight against Covid-19."

Is America's coronavirus future 'good,' 'bad,' or 'ugly'? It's all three.

"We have to end Covid-19, not just at home, which we're doing, but everywhere," Biden said. "There's no wall high enough to keep us safe from this pandemic or the next biological threat we face, and there will be others. It requires coordinated multilateral action."

Reaction

Some public health experts praised the move, with Jennifer Nuzzo, an epidemiologist and senior scholar at the Johns Hopkins Center for Health Security, saying it's "an extraordinary development" that "sends a profound signal in terms of U.S. commitment to global health security and willingness to help end this pandemic for the world and the United States."

But Thomas Bollyky, a senior fellow at the Council on Foreign Relations and director of its global health program, said the announcement is "meaningful but not sufficient on its own."

Bollyky noted that 500 million vaccine doses is about six times what COVAX has distributed to this point, but it's just a quarter of the two billion it intends to distribute by the end of the year.

"These Pfizer doses will go to many countries," he said. "The big question is, in what order and in what amount? That will have significant bearing on what the public health impact of the commitment will be" (Pager/Rauhala, Washington Post, 6/9; LaFraniere et. al., New York Times, 6/9; Siddiqui/Shah, Wall Street Journal, 6/10; Williams, The Hill, 6/9; Sink, Bloomberg, 6/9; Tirrell, CNBC, 6/9).