YouTube has removed two videos of California doctors whose calls to ease coronavirus lockdowns have become the newest ammunition used by conservative media and fringe activists in their calls to end government measures to slow the spread of the disease.

The doctors, Dan Erickson and Artin Massihi of Bakersfield, California, downplayed the risk of the coronavirus and asserted that stay-at-home measures were unnecessary. They also promoted a conspiracy theory that doctors were falsely attributing unrelated deaths to COVID-19.

Facebook, however, has not removed the doctor’s videos, and dozens of others remain on YouTube, some in full, some sliced into segments, racking up hundreds of thousands of views. One video on Facebook has been viewed more than 9 million times.

Facebook declined to comment.

The different reactions of YouTube and Facebook highlight the challenges of moderating high-stakes misinformation as it goes viral, especially when the source is considered expert opinion and produced by a usually trusted source. Facebook, YouTube and other tech platforms quickly took aggressive stances against coronavirus misinformation in the early days of the public health crisis but have struggled to contain the varied forms of false claims that have included everything from conspiracy theories about Bill Gates to racist claims about Asian people.

Those moderation efforts have been further complicated by the growing politicization of the pandemic, with many supporters of President Donald Trump seizing on misleading claims or outright falsehoods related to the coronavirus and state lockdowns, and most Democrats expressing concern about the outbreak.

“We quickly remove flagged content that violate our Community Guidelines, including content that explicitly disputes the efficacy of local healthy authority recommended guidance on social distancing that may lead others to act against that guidance,” YouTube spokesperson Ivy Choi said in a statement.

“However, content that provides sufficient educational, documentary, scientific or artistic context is allowed,” Choi said.

The video removed by YouTube showed a one-hour news conference livestreamed by local media, including NBC and ABC affiliates in Bakersfield. Dressed in medical scrubs, Erickson and Massihi, owners of several urgent care centers in the area, presented data from 5,213 COVID-19 tests, about half of the tests administered in Kern County. The data, they claimed, showed that the coronavirus was widespread in the community already, but had caused few deaths. Their data, they said, supported the need to rethink state stay-at-home measures enacted to slow the spread of the coronavirus.

Further, Erickson dismissed the need for protective measures including masks, and claimed COVID-19 death numbers were inaccurate, citing other unnamed doctors in Wisconsin and California who had told him they were urged to list the disease as a cause of death, even if unrelated.

“Are we being pressured to add COVID to maybe increase the numbers and make it look a little bit worse than it is? I think so,” Erickson said.

Doctors, public health officials and epidemiologists were all quick to point out a number of flaws in the doctors’ claims.

On Monday, the American College of Emergency Physicians and the American Academy of Emergency Medicine released a joint statement critical of Erickson and Massihi’s opinions as expressed in the video calling them “reckless and untested musings” that “do not speak for medical societies and are inconsistent with current science and epidemiology regarding COVID-19.” The statement also suggested their ownership of urgent care centers made it appear as if the doctors were “releasing biased, non-peer reviewed data to advance their personal financial interests without regard for the public’s health.”

Carl Bergstrom, a professor of biology at the University of Washington and author of “Calling Bulls—: The Art of Skepticism in a Data-Driven World,” debunked the video’s claims on Sunday.

In a series of tweets, Bergstrom criticized the doctors’ use of patients from their urgent care clinic to suggest the national risk of death from COVID-19 was less than the flu, calling their analysis “absurd” and “highly biased.”

Others highlighted the doctors’ possible political motives, noting a selfie-video of Erickson demonstrating in support of the president, which was posted to a Facebook page for the newly-formed political organization Trump Citizens of California.

“We’re out Trumpin’,” Erickson said in the video, while waving a flag from the roadside in the now-private or deleted video archived by NBC News. “The time for silence is over.”

Erickson and Massihi did not respond to a request for comment. Massihi posted a video to his personal Facebook page on Tuesday thanking supporters, while insisting their comments were only meant to share their own data, not to drive national or even state policy, a seeming walk back from the video’s anti-stay-at-home messaging. By Wednesday, Massihi’s profile had been made private.

Erickson dismissed criticism that his claims were reckless or dangerous on Tuesday in an interview with a Los Angeles Fox News affiliate.

“You have to think about this as a balancing act,” he said. “You have to balance the collateral damage with the medical illness and say which one has a worse effect on society.”

Warnings from other health professionals did little to stop the video from going viral on nearly every social media platform this week, driven by influential conservative accounts like Ben Shapiro, Mark Levin and dozens of others who have voiced support for reopening the states.

By Wednesday, the video had been seen at least 15 million times and shared by hundreds of thousands of accounts on both Facebook and YouTube, according to an NBC analysis of the most popular videos across platforms. The video had also been spread widely in dozens of private Facebook groups dedicated to statewide protests against states’ quarantine measures and the anti-vaccination movement, where activists fear a coming coronavirus vaccine.

That boost has pushed the doctors into mainstream conservative media.

They appeared on Laura Ingraham’s Fox News show on Monday, and Fox News host Tucker Carlson promoted the doctors on his show Tuesday, and condemned YouTube’s moderation. “When all of this is finally over,” Carlson said, “we’ll see this moment, what YouTube just did, as a turning point in the way we live in this country.”

“The only justification for taking it down was that the two physicians on screen had reached different conclusions from the people currently in charge. It was a form of dissent from orthodoxy,” Carlson said.