Trump administration officials on Monday denied a report that the federal government turned down an offer from Pfizer earlier this year to purchase additional doses of its COVID-19 vaccine.

The administration's Operation Warp Speed signed a nearly $2 billion contract with Pfizer and its partner BioNTech in July for the rights to 100 million doses. 

Under the agreement, the government will pay the companies $1.95 billion upon the receipt of the first 100 million doses, following authorization by the Food and Drug Administration (FDA). The contract gave the administration the ability to acquire up to an additional 500 million doses.

According to The New York Times, the administration declined this summer when offered the opportunity to purchase additional doses. 

As a result, Pfizer may not be able to provide more of its vaccine to the United States until June because of its commitments to other countries.

But an administration official said nobody turned down additional Pfizer doses. The official said the U.S. has contracts with five other companies for a combined guarantee of 3 billion doses as well as the option for more.

"Anyone who wanted to sell a guarantee, without an EUA [emergency use authorization] approval, hundreds of millions of doses back in July and August, was just not going to get the government's money," the official said.

Pfizer and BioNTech developed their vaccine without the aid of federal funding, unlike other companies such as Moderna. The U.S. is paying for distribution only, so the price could be higher than what other countries are paying.

"We have continued to negotiate with all of the vaccine manufacturers, particularly the ones who now have good data, those who are in the window for an EUA authorization. We're not going to talk about those because those negotiations are underway," the official said.

In a statement, Pfizer said any additional doses beyond the 100 million "are subject to a separate and mutually-acceptable agreement. The company is not able to comment on any confidential discussions that may be taking place with the U.S. government."

Pfizer's vaccine could get FDA authorization as soon as this week. But the administration anticipates only 6.4 million doses will be available before the end of the year, which is enough for 3.2 million people.

Federal health officials said they expect to have enough doses from Pfizer and Moderna to vaccinate a total of 20 million people by the end of the year, a fraction of the country's 330 million people.