As Fauci's critics expressed doubts over his role in 'debunking' that the Covid-19 virus was leaked from a lab in Wuhan, China, US President Joe Biden reiterated his confidence in Fauci.

According to reports, in an email exchange in April 2020, an executive at a health charity thanked the top US coronavirus advisor for backing the theory that the virus wasn't leaked from a lab.

However, Fauci told CNN that had an 'open mind' about the origin of the virus and that the email issue was blown out of proportion.

"You can misconstrue it however you want," he told CNN.

"That email was from a person to me saying 'thank you' for whatever it is he thought I said, and I said that I think the most likely origin is a jumping of species. I still do think it is, at the same time as I'm keeping an open mind that it might be a lab leak.

"The idea I think is quite far-fetched that the Chinese deliberately engineered something so that they could kill themselves as well as other people. I think that's a bit far out," he added.

The issue started after Peter Daszak, head of EcoHealth Alliance, a New York-based non-profit group emailed Dr Fauci in April 2020 and thanked him for publicly debunking the lableak theory.

Reports said The National Institutes of Health, a US public health agency, gave $600,000 to the Wuhan Institute of Virology from 2014-19 via a grant to the New York-based non-profit group for the purpose of researching bat coronaviruses.

Replying to Daszak's mail, Fauci replied, "Many thanks for your kind note."

Peter Daszak, President of EcolHealth Alliance of New York and an eminent zoologist, had reportedly subcontracted work on bat-based corona virus and spoke protein to Dr. Shi Zheng-li of WIV. 

As the president's chief medical advisor came under fire, White House press secretary Jen Psaki told a press briefing on Thursday: "The president and the administration feel that Dr Fauci has played an incredible role in getting the pandemic under control, being a voice to the public throughout the course of this pandemic."

According to a Vanity Fair investigation report, officials from the US Department of State met and discussed the origins of coronavirus on 9 December 2020.

It said that the meeting decided not to explore claims about gain-of-function experiments at the Wuhan lab as the US government wanted to keep unwelcome attention at bay, owing to its funding such research.

"Gain-of-function studies involve altering pathogens to make them more transmissible in order to learn more about how they might mutate," a BBC report added.

Meanwhile, the Financial Times quoted Fauci as stating that he wanted to see the medical reports of three people who fell ill in November 2019 just before the first Covid-19 case was reported.

"I would like to see the medical records of the three people who are reported to have got sick in 2019. Did they really get sick, and if so, what did they get sick with?" Fauci told the Financial Times on Thursday.

The disease expert also urged Beijing to release the medical records of six miners who fell ill after entering a bat cave in 2012 in China's Yunnan province, reports said.

"Three miners died, and Chinese researchers later visited the cave to take samples from the bats," the BBC reported.

Fauci said that it is entirely conceivable that the origins of Sars-Cov-2 was in that cave and either started spreading naturally or went through the lab.

During congressional testimony on May 26 Fauci said he believed the Chinese researchers while replying to Republican Senator John Kennedy of Louisiana. Earlier on May 12, the disease expert had denied the US' involvement and funding in the research at the Wuhan lab.

While Joe Biden has thrown his weight behind Fauci, the former's predecessor Donald Trump has come down hard.

"What did Dr Fauci know about 'gain of function' research, and when did he know it?" Trump wrote on Thursday.

"China should pay Ten Trillion Dollars to America, and the World, for the death and destruction they have caused," demanded the former US President.

On Thursday, Republican lawmaker Steve Scalise demanded in a letter that Fauci testify before Congress on the "US government's role in funding research that may have contributed to the development of the novel coronavirus".