National Institutes of Health director Dr. Francis Collins praised the Trump administration on Sunday for the "breathtaking" success of Operation Warp Speed in getting multiple effective coronavirus vaccines developed and tested within one year of the virus outbreak.

"The Operation Warp Speed, for which I give a great deal of credit to [former HHS Secretary Alex Azar], was a effort that many of us were not initially convinced was going to be necessary. And it was thought about as a Manhattan Project," Collins told Axios.

"Those words were used sometimes to describe what needed to happen in order to get all parts of the government together in an unprecedented way to test up to six vaccines in rigorous trials, and to do this at-risk manufacturing, so that if any of those trials happened to work, you would already have doses ready to go into arms."

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When former President Donald Trump last year predicted a coronavirus vaccine would be ready by the end of 2020, multiple media outlets declared it a "pipe dream" and having vaccines that fast would require a "miracle." However, both Moderna and Pfizer developed effective vaccinations that have entered tens of millions of arms.

"The fact that we, in December, had not one but two vaccines that had gone through trials ... and had been judged safe and effective by a very rigorous and very public FDA process is just breathtaking," Collins said, adding it was completed five years faster than had ever been done before.

Operation Warp Speed, first announced in May, was the Trump administration's plan to coordinate with federal and private entities to quickly develop and distribute safe COVID-19 vaccines. The vaccinations have proven highly effective in preventing the disease, and experts agree they are the key to the quickest return to normal life.

White House chief medical adviser Dr. Anthony Fauci directs the National Institute of Allergy and Infectious Diseases, whiich falls under the NIH, and has also praised the success of Operation Warp Speed. 

Collins said the recruitment of Dr. Moncef Saloui, the chief medical adviser for the operation, was "an incredibly important step forward that the administration deserves credit for, because that did motivate a lot of actions, a lot of coordination."

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The Biden administration has consistently panned its predecessor for making it "start from scratch" on coronavirus vaccine distribution, but the U.S. was already at around 1 million vaccinations per day when Trump left office and now leads the world in total vaccinations.

Fox News' Peter Aitken contributed to this report.