The vaccine breakthroughs from Pfizer and Modernaare incredible news, for a small sliver of the world.

The big picture: Wealthy countries like the U.S. have secured their access to those vaccines and others and are increasingly confident they'll begin mass vaccination this spring. But according to research from Duke University's Global Health Institute, there likely won't be enough doses to cover the entire global population until 2024.

Driving the news: Pfizer has agreed to sell at least 1.1 billion doses combined to the U.S., EU, Canada, Japan and U.K. That's nearly all of the 1.3 billion it aims to produce by the end of 2021.

• Its vaccine also has to be stored at -80C, a requirement that few facilities in the developing world are equipped to handle.

Moderna's announcement today that its vaccine appears to be 95% effective should be better news for countries outside of the U.S. and Europe.

• The storage requirements aren't as onerous and it's part of the COVAX portfolio of vaccines the World Health Organization and other groups plan to distribute to lower-income countries.
• Tal Zaks, Moderna's chief medical officer, told the Axios Pro Rata podcast today that the 20 million doses it will produce this year will all go to the U.S., which helped fund the vaccine's development and has purchased at least 100 million doses in total.

• Moderna also has deals with the EU and Japan. After today's news prompted questions over why it hadn't invested in the Moderna vaccine, the U.K. government announced it was in "advanced talks" to ensure its access.
• The flipside: "There is a dialogue ongoing with COVAX. I don't think we have quite aligned with them on how many doses and when those doses would be available for the COVAX collaboration," Zaks said.

What to watch: The best hope for a vaccine that will be quickly produced at scale for developing countries may lie with Oxford and AstraZeneca, which expect to release efficacy data for their vaccine by year's end.

• That vaccine is also part of the COVAX portfolio and has a deal with the world's highest-capacity vaccine manufacturer, the Serum Institute of India.
• The Serum Institute is slated to produce two-thirds of the doses promised to low- and middle-income countries by AstraZeneca, Johnson & Johnson, Novavax and Sanofi, per WaPo.

State of play: Canada has purchased enough doses to vaccinate its population five times over, according to the Duke study. It's one of several countries hedging their bets to ensure access even if some vaccines aren't approved.

• Several middle-income countries have cut smaller-scale deals with pharmaceutical companies or vaccine-producing countries like China or Russia.
• Brazil, Egypt and India are among those that expect to receive access because they have significant vaccine production capacity or are hosting clinical trials.

Much of the rest of the world is relying on COVAX.

• Wealthier countries will effectively subsidize access for poorer ones, with an initial wave of distribution intended to reach 3% of each country's population and a second wave bringing that to 20%, potentially by the end of 2021.

With its bulk orders for six vaccines, the U.S. could find itself in control of around one-quarter of the world's near-term supply, according to the Duke analysis.

• Along with Russia, it's also one of the very few non-participants in COVAX.

Why it matters: "I think we're going to see the tension between vaccine nationalism and vaccine diplomacy, where deploying some of our surplus vaccine doses in a strategic way becomes part of the U.S. foreign policy," says Dr. Krishna Udayakumar, director of Duke's Global Health Innovation Center.

Joe Biden plans to re-engage with the WHO, though his team has not said whether he would participate in COVAX.

• China is already promising access to its vaccines to friendly or neighboring countries.
• Russia, meanwhile, has cut deals with several countries for access to its vaccine, which Vladimir Putin has used to emphasize Moscow's global clout.
• There are now conversations underway to determine whether and how wealthy countries that purchased more doses than they ultimately need will be able to steer the surplus into COVAX, Udayakumar says.

The bottom line: Beyond the humanitarian and diplomatic considerations, it's also clear that the pandemic won't be over anywhere — as a public health crisis or as a drag on the global economy — until it's under control everywhere.