Outgoing National Institutes of Health Director Dr. Francis Collins told Fox News on Sunday that he's "sorry" the Wuhan lab-leak theory has become such a "huge distraction" for the country, despite there being "no evidence" to support it.

Collins joined "Fox News Sunday" on his last day in office after more than a decade in the agency's top position. The geneticist and physician tapped by President Barack Obama to lead the NIH in 2009 dodged questions about his efforts to discredit the lab-leak theory at the onset of the pandemic, maintaining the most plausible explanation is that the virus spread through animal-to-human transmission.

"I’m really sorry that the lab leak has become such a distraction for so many people because frankly, we still don’t know," Collins told host Bret Baier.

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"There is no evidence really to say. Most of the scientific community, myself included, think that is a possibility, but far more likely, this was a natural way in which a virus left a bat, maybe traveled through some other species and got to humans."

Dr. Anthony Fauci and Dr. Francis Collins, Director of the National Institutes of Health, on Capitol Hill.

Top infectious disease experts Dr. Anthony Fauci and Dr. Francis Collins, Director of the National Institutes of Health, on Capitol Hill. (J. Scott Applewhite-Pool/Getty Images; Greg Nash- Pool/Getty Images)

Collins said in October of this year that accusations surrounding the agency's involvement in gain-of-function research and the Wuhan Institute of Virology had "absolutely" nothing to do with his resignation.

Still, emails released by BuzzFeed that reveal private correspondence between Collins and Dr. Anthony Fauci suggest a deliberate effort to downplay theories that the coronavirus originated in the Wuhan lab and, whether deliberately or inadvertently, their funding had any involvement.

"We won’t know unless China decides to open up on this which they have not done, and shame on them for that," Collins said, reiterating that "this has been a huge distraction" for the scientific community. 

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"We in this country have somehow gotten all fractured into a hyperpolarized politicized view that never should have been mixed with public health," Collins said. "It has been ruinous and history will judge harshly those people who have continued to defocus the effort and focus on conspiracies and things that are demonstrably false. Shame on all us that we’ve gotten into this kind of pickle."

National Institutes of Health Director Dr. Francis Collins testifies before a Senate Appropriations Subcommittee

National Institutes of Health Director Dr. Francis Collins testifies before a Senate Appropriations Subcommittee looking into the budget estimates for National Institute of Health (NIH) and the state of medical research on Capitol Hill, May 26, 2021 in Washington, D.C.  (Sarah Silbiger-Pool/Getty Images)

Collins made headlines on Friday after the House Select Subcommittee on the Coronavirus Crisis released an email where he expressed deep concerns about the herd immunity strategy being advocated by "fringe epidemiologists," and called for "a quick and devastating published takedown" of the three experts promoting the herd immunity strategy known as "The Great Barrington Declaration."

Collins told Baier that he is "not going to apologize," for his words, arguing that "hundreds of thousands of people would have died if we had followed that strategy."

"I did write that, and I will stand by that," Collins said. "Basically, these fringe epidemiologists who really did not have the credentials to be making such a grand sweeping statement, were saying just let the virus run through the population and eventually then everybody would have had it and everything will be okay."

A man walks through a deserted part of Johannesburg's OR Tambo's airport in South Africa.

A man walks through a deserted part of Johannesburg's OR Tambo's airport in South Africa. The World Health Organization urged countries around the world not to impose flight bans on southern African nations due to concern over the new omicron variant. (AP/Jerome Delay)

The United States recently surpassed 50 million COVID-19 cases and 800,000 deaths since the start of the pandemic. Despite the staggering numbers, Collins maintained that "hundreds of thousands of people would have died if we had followed that strategy."

"So I'm sorry I was opposed to that, I still am, and I'm not going to apologize for it," he said. 

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As for the new omicron variant, Collins said the U.S. should brace for a "world of trouble" the next couple of months, based on its higher transmissibility than the previous strains, which "pale by comparison."

Baier pointed to recent data out of South Africa that could point to milder symptoms and fewer hospitalizations from omicron.

"I am hopeful that that is an indication that while incredibly contagious, this virus may be a bit less likely to make people sick," Collins said, "and obviously that is something we have got to hope for, or our health systems are going to be overwhelmed."