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While the U.S. is expected to pledge $4 billion to help with global vaccine efforts, the Biden administration will not donate any of the country's doses until most Americans are vaccinated, a senior official told reporters on Thursday.

The official said the U.S. is "focused on American vaccinations and getting shots into arms here" while also "determining the timeline when we will have a sufficient supply in the United States and be able to donate surplus vaccines." On Tuesday, President Biden said he expects every American who wants a vaccine will be able to get one by July.

Worldwide, just 10 countries have administered 75 percent of all vaccines, with 150 countries yet to receive even a single dose. The distribution of vaccines has been "wildly uneven and unfair," United Nations Secretary General António Guterres said Wednesday, and "vaccine equity is the biggest moral test before the global community." French President Emanuel Macron on Thursday called on the U.S. and European nations to donate up to 5 percent of the vaccine doses they have ordered.

Biden is set to announce the $4 billion funding for global vaccine efforts during Friday's Group of 7 virtual meeting. The first $2 billion will be used to purchase vaccine doses for 92 countries, with the rest donated over the next two years to increase vaccine manufacturing and delivery, Politico reports.