The US could have an estimated 300 million excess Covid-19 vaccine doses by the end of July, according to a report from Duke University.
Researchers used data on the US government's advance purchase commitments with drug giants to arrive at the estimate.
The country has commitments for vaccines with Pfizer, Moderna, Johnson & Johnson, AstraZeneca and Novavax.
The AstraZeneca and Novavax shots are yet to receive emergency use authorization in the US, according to the Food & Drug Administration (FDA).
The report authors also reviewed vaccine production timelines and used US Census data to estimate demand.
Their estimate accounts for the nation retaining enough doses for most children in the country.
The researchers also assume that 75% of the US population will receive a two-dose vaccine and 25% will receive a single shot Johnson & Johnson vaccine.
Given the recent pause that will limit use of the Johnson & Johnson vaccine in the US, their projections may not be entirely accurate.
Regardless, the US and other wealthier countries should expect to have a vaccine surplus in the future, the authors write.
Currently, 10 nations that amount to less than half the world’s population have used three-quarters of Covid-19 vaccine doses, but many poorer countries still don’t have a supply at all.
“The world’s wealthiest nations have locked up much of the near-term supply. At the current rate vaccines are being administered, 92 of the world’s poorest countries won’t vaccinate 60% of their populations until 2023 or later,” write Dr. Krishna Udayakumar, director of the Duke Global Health Innovation Center and Dr. Mark McClellan, director of the Duke-Margolis Center for Health Policy.
“Now is the time to advance an effective plan for distributing additional excess doses as they become available."
The authors say the US should invest more to strengthen the COVAX vaccine scheme and make excess doses available to other nations.
They also write that the US should support other nations so they can produce vaccines on their own.