The program, known as COVAX, asked Wednesday for $5.2 billion in order to continue operations over the coming months.
Just a few days ago, the World Health Organization (WHO) announced that COVAX had delivered 1 billion doses since shipments started almost a year ago.
A Jan. 15 shipment of 1.1 million vaccine doses to Rwanda included the billionth dose supplied and COVAX has made deliveries to 144 countries thus far.
In a press release, the agency wrote last week that the program's ambition was "compromised by hoarding/stockpiling in rich countries, catastrophic outbreaks leading to borders and supply being locked."
"And a lack of sharing of licenses, technology and know how by pharmaceutical companies meant manufacturing capacity went unused," it noted.
This comes after WHO Director-General Tedros Adhanom Ghebreyesus called on leaders to back a campaign to vaccinate 70% of countries' populations by July.
Initially, the goal was to deliver 2 billion doses by the end of 2021, but most of the world's vaccine doses have gone to wealthy nations who locked in contracts and COVAX lacked money when deals were being made.
Seth Berkley, the CEO of Gavi, the global health organization that co-founded the COVAX initiative, explained that "we right now are basically out of money."
Less than 10% of people living in low-income countries have received at least one dose.
More than 60% of the world’s overall population has been vaccinated, with some also receiving boosters.
In the U.S., Centers for Disease Control and Prevention (CDC) data shows 209.5 million people are fully vaccinated and 81.7 million have received a booster shot, as omicron continues to infect around the nation.
The Associated Press contributed to this report.