But those 25 million doses represent just a fraction of the global demand for Covid-19 vaccines in low- and middle-income countries that have struggled to source shots on their own. Despite the United States’ growing vaccine surplus, officials at the White House, State Department and U.S. Agency for International Development spent months mired in intense debate about whether to send doses to the rest of the world and how to determine which countries needed them most, seven senior U.S. officials told POLITICO.

“We had an obligation to try and move as quickly as possible to get [the doses] over there,” one senior health official said. “We’ve got plenty of doses. Now we’re finally moving. But we didn’t need to take this long to do it.”

Biden said in late April that the U.S. would send 60 million doses of AstraZeneca’s vaccine abroad by July 4, a commitment made amid growing global concern about sharp spikes in Covid-19 cases and deaths in India. On May 17, Biden said the U.S. would donate an additional 20 million doses — a mix of Pfizer, Moderna and Johnson & Johnson’s shots — by the end of June.

But the world waited for months for a hint of which countries would share in the United States’ vaccine bounty. In recent weeks the virus has overwhelmed countries across South Asia and South and Central America, leaving them unable to treat their citizens let alone vaccinate them.

Early in the Biden administration, White House, national security and health officials agreed that their goal was for the U.S. to become the world leader in vaccine donations, multiple senior administration officials told POLITICO. But they disagreed on when to start shipping out doses, how many to send, and whether to even call them donations.

Officials also split on how the U.S. should decide where to send the vaccine. Dozens of countries across the world were at risk for uncontrollable virus surges. The U.S. government wanted to ensure that the doses it did ship would be distributed equitably and help the maximum number of people possible.

The administration did not begin working on a framework for donations until Gayle Smith, the coordinator of the global COVID response and health security at State, stepped into office in April.

It took until last week for the White House to finalize its plan for the initial donation of 25 million doses after coming under increasing pressure from world leaders and members of Congress. In particular, Indian Foreign Minister Subrahmanyam Jaishankar pressed State and National Security officials about the hold up in vaccine shipments, two senior officials with knowledge of those conversations said. Biden had said in April that he intended to send Covid-19 vaccines to India; since then, millions of Indians have contracted Covid-19 and tens of thousands of people have died, but the U.S. has not shipped the country any shots.

The first wave of donations announced Thursday includes 19 million doses that will be distributed through COVAX. Six million of those will go to countries in South and Central America, including Brazil, Paraguay and El Salvador; seven million doses will be sent to Asian countries, including India, Nepal, Pakistan and the Philippines. Another 5 million doses will go through COVAX to African countries that will be selected in coordination with the African Union. The U.S. will also send a total of 6 million doses directly to allies and “regional priorities,” including Mexico, Canada, West Bank and Gaza, Ukraine, Egypt and Iraq, the White House said.

The donation will come from the U.S. stockpile of Johnson & Johnson, Pfizer and Moderna vaccines. But that was not the original plan. The administration originally planned to start donations by drawing on 60 million doses of AstraZeneca’s vaccine manufactured at a Baltimore plant — but those shots have been tied up in a lengthy Food and Drug Administration safety review.

In March, the Baltimore facility run by contract manufacturer Emergent BioSolutions accidentally contaminated 15 million Johnson & Johnson doses with the active ingredient of AstraZeneca’s vaccine. Production at the plant stopped in April and the FDA began investigating the matter. Since then, the agency has been trying to determine whether any of the other millions of doses of the J&J and AstraZeneca vaccines made by Emergent were contaminated. While available testing methods can identify major contamination problems, they are not always capable of tracing small amounts of contamination.

Officials had said they needed the FDA to sign off on those doses as safe before the administration could announce which countries would receive vaccine donations.

For weeks this spring, administration officials told POLITICO they expected the FDA investigation to come to a conclusion soon — enabling the White House to begin shipping shots abroad. But as the days passed by, it became clearer to the Biden team that the FDA investigation needed more time, three officials working on the federal government’s Covid-19 global response said.

The doses were tested for contamination, but the agency worried that low levels of contamination could escape detection. The FDA ultimately asked AstraZeneca and Johnson & Johnson to run risk assessments of the potential effects of any trace contamination in the Emergent doses — contamination that would not necessarily impact the overall safety of the vaccine. The agency took extra care with its review in part because the administration planned to ship many of the doses abroad.

That caution has frustrated not only foreign leaders and members of Congress, but also personnel at other U.S. agencies. American diplomats overseas have pushed the State Department to send vaccine abroad as a way to counter Russia and China, which are using their homegrown shots to win political concessions from recipients. And senior health officials have told the White House that the U.S. has more than enough vaccine in its stockpile for America’s needs.

“We will work as expeditiously as possible,” National Security Adviser Jake Sullivan told reporters Thursday. “This is certainly a complex operational challenge but one that we will take on. Our goal is in service of ending the pandemic globally. We want to save lives and thwart variants that place all of us at risk. Most important, this is just the right thing to do.”

Disagreement among top officials at State, the National Security Council and the White House over the donations began in early April, officials said. The White House was wary of shipping vaccine abroad when U.S. demand for the shots was falling, making it unclear how many doses would be needed at home over the next six months. Other senior health and national security officials pushed back, saying internal vaccine projections showed the U.S. could spare millions of doses from its stockpile to lower and middle income countries.

“It’s been a … well, let’s just say it hasn’t been an easy few weeks,” said one of the seven senior administration officials working on vaccine-donation effort. “The fact is we couldn’t get these doses overseas quick enough. We needed to send them sooner. But we couldn’t.”

Two national security officials familiar with deliberations on vaccine requests told POLITICO the administration was originally concerned about the situation in South Asia, including Nepal and the Philippines, but that the focus has shifted in recent days to South America and other countries in the Northern Hemisphere.

Beyond the national security and health implications of sending vaccines to the rest of the world, senior administration officials in the White House also discussed in several high level meetings with the NSC and State Department about the optics of sending doses to the world when the U.S. was far from reaching herd immunity through vaccination.

“I think there was a real sense that we might not be able to get where we want to go with the vaccine in this country,” one senior administration official with knowledge of the White House conversations said. “And we wanted to approach this with an America first attitude. Let’s get our own people taken care of first before we move to help others.”

But continuing to wait became untenable.

“A major tension within the administration and certainly outside the administration has been how much of the focus of the White House should be on U.S. response versus doing more globally,” said Ashish Jha, dean of Brown University’s School of Public Health. “It’s been very clear which side has been winning that debate.”

The vaccine donations supplement a broader effort in the Biden administration to provide Covid-19 humanitarian assistance to the rest of the world. USAID is leading the effort in trying to identify life saving supplies such as masks, gloves and oxygen components in the supply chain, buy the products and find ways to ship them to countries across the world.

That effort has slowed in recent weeks, even after the administration said it would provide supplies to India, two officials with knowledge of the matter said. Prices for personal protective equipment are rising again and oxygen components are increasingly difficult to come by. Officials said there is an added hurdle of finding enough cargo space to ship the materials overseas.