Dr Scott Atlas, a science adviser to President Donald Trump who was skeptical of measures to control the coronavirus outbreak, is leaving his White House post.
A White House official confirmed that the Stanford University neuroradiologist, who had no formal experience in public health or infectious diseases, resigned at the end of his temporary government assignment. Atlas confirmed the news in a Monday evening tweet.
Atlas joined the White House this summer, where he clashed with top government scientists, including Dr Anthony Fauci and Dr Deborah Birx, as he resisted stronger efforts to contain the Covid-19 pandemic that has killed more than 267,000 Americans.
Atlas has broken with government experts and the overwhelming consensus of the scientific community to criticise efforts to encourage face covering to slow the spread of the virus.
Just weeks ago on Twitter he responded to Michigan's latest virus restrictions by encouraging people to "rise up" against the state's policies.
He has also been criticised for calling for states to reopen, and called lockdowns "extremely harmful to Americans".
His views also prompted Stanford to issue a statement distancing itself from the faculty member, saying Atlas "has expressed views that are inconsistent with the university's approach in response to the pandemic".
"We support using masks, social distancing, and conducting surveillance and diagnostic testing," the university said on November 16.
"We also believe in the importance of strictly following the guidance of local and state health authorities."
Earlier this month, Atlas came under fire for suggesting that people should invite their elderly relatives for Thanksgiving because it might be their last.
His advice contradicted that of most public health experts.
Atlas made the remark as he attacked lockdowns on Fox News for "isolating" people.
"This kind of isolation is [also] a tragedy of the elderly who are now being told 'don't see your family at Thanksgiving'," he told host Martha MacCallum at the time.
"For many people this is their final Thanksgiving, believe it or not. We have to have a policy... which is a whole person policy. It's not just about stopping cases of Covid."
His advice contradicted that of Dr Fauci, who said people need to avoid large gatherings this year - especially those involving the elderly.
"People should be very careful about social gatherings, particularly when members of the family might be at a risk because of their age," Fauci said last month.
"You may have to bite the bullet and sacrifice that social gathering unless you're pretty certain that the people that you're dealing with are not infected."
Dr David Spiegel of the Stanford School of Medicine also condemned Atlas' stint as scientific adviser to Trump.
"What Atlas has done is an embarrassment to the university", Spiegel said.
"He is using his real affiliation with Hoover [Stanford's Hoover Institute] to provide credibility in issues he has no professional expertise to discuss in a professional way."