Photo: PAHO. The program will help to make vaccines affordable for even the poorest countries.

President Biden is under increasing pressure to share the U.S. vaccine stockpile with the rest of the world.

The federal government has been amassing doses, growing its supply into what will likely become a surplus, as the rest of the world struggles with shortages. The U.S. has purchased enough vaccines to immunize every adult in the country three times over.

The supply is likely to grow.This week, Biden announced he had directed the administration to purchase an additional 100 million doses from Johnson & Johnson.

The White House said the extra doses could be a backstop for possible manufacturing issues, help vaccinate children, or serve as booster doses if they become necessary to fight against variants of the virus.

If finalized, the deal would not be fulfilled until the second half of the year, but would give the U.S. a total of 200 million shots from Johnson & Johnson, enough for 200 million people.

When asked at the White House event about the widening gap between the U.S. and the rest of the world, Biden acknowledged the global nature of the pandemic but said his goal is to bring COVID-19 under control in America first.

“This is not something that can be stopped by a fence, no matter how high you build a fence or a wall,” Biden said. “So we’re not going to be ultimately safe until the world is safe. We’re going to start off making sure Americans are taken care of first, but we’re then going to try to help the rest of the world.”

“If we have a surplus, we’re going to share it with the rest of the world,” Biden added, noting that the U.S. has already committed $4 billion to COVAX, the World Health Organization-led program for distributing the vaccine across the world.

On Friday, Biden committed to working with the leaders of Australia, India and Japan to expand vaccine manufacturing and delivery in Asia. The new commitment is aimed at addressing shortages in vaccines in Southeast Asia.

Yet administration officials reiterated that the United States will not donate any vaccines until the full American population is inoculated, and did not say what threshold the country would set before considering exporting vaccines.

Experts and global health advocates think the U.S. has the ability to donate vaccines to other countries without significantly impacting their availability to Americans, but has been unwilling to make such a plan.

“The world is currently facing a vaccine access crisis and the Biden administration has not yet established a clear framework or timeline for distributing excess vaccine doses while simultaneously vaccinating the U.S.’ domestic population,” said Sarah Swinehart, a spokeswoman for The ONE Campaign.

The global aid organization UNICEF, which is working with COVAX to deliver vaccines, has said countries that have vaccinated their own health workers and highest risk populations should share vaccine doses with other countries.

In the U.S., demand still outpaces supply, but that is beginning to change. States are opening up eligibility, and President Biden said he expects there will be enough supply for every American who wants a vaccine by the end of May.

During a speech Thursday evening, Biden said every adult will be able to sign up for a vaccine no later than May 1.

But pressure and frustration among allied countries is only growing after the administration said it has been keeping tens of millions of doses of a vaccine made by AstraZeneca in storage.

The Trump administration ordered 300 million doses of the vaccine, but issues with clinical trials have held up its authorization and the Food and Drug Administration (FDA) is still waiting on additional data.

The vaccine has been authorized for emergency approval in the European Union, and is the primary vaccine being used by COVAX in poor countries. But even though it has not been authorized in the U.S., Biden administration officials said they are holding on to the supply.

White House coronavirus coordinator Jeff Zients told reporters the U.S. has a “small inventory” of the AstraZeneca vaccine on hand so it can be ready to distribute quickly if the company receives FDA clearance in the coming weeks.

“We’re following the exact same process that we did with the other three now-approved vaccines; Moderna, Pfizer and J&J,” Zients said

White House press secretary Jen Psaki said the U.S. has rejected all requests from other countries to share doses of its vaccines.

“There have been requests around the world from a number of countries who have requested doses from the United States, but we have not provided doses from the U.S. government to anyone,” Psaki said.

Psaki said the administration is trying to cover all contingencies and ensure Americans are getting put first.

“We want to make sure we have maximal flexibility, that we are oversupplied and over prepared and that we have the ability to provide vaccines — whatever the most effective ones are — to the American public,” Psaki said. “There are still 1,400 people who are dying in our country every single day and we need to focus on addressing that.”