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Social media companies Facebook and Twitter have ramped up oversight of misinformation about the coronavirus on their platforms, taking more direct measures to identify and take down misleading propaganda, and over the weekend, invoked their broadening oversight to force the removal of posts by Brazilian President Jair Bolsonaro. Both companies have previously been loath to remove content posted by world leaders even if their posts were demonstrably false. Twitter, however, has revised its terms of service to expressly disallow content that “goes directly against guidance from authoritative sources of global and local public health information.”

Over the weekend, two tweets by the Brazilian president were removed that overhyped the effectiveness of the treatment hydroxychloroquine. Facebook followed suit on Monday by removing the video from Facebook and Facebook-owned Instagram. “We remove content on Facebook and Instagram that violates our Community Standards, which do not allow misinformation that could lead to physical harm,” a Facebook spokesperson told BuzzFeed News. Bolsonaro, a right-wing populist, has preached and pushed conspiracy theories since taking office some 18 months ago and has, like Donald Trump has at times, cast doubt over the legitimacy and seriousness of the pandemic.

The deletion of Bolsonaro’s posts comes on the heels of Twitter removing a post last week by Venezuelan President Nicolás Maduro hyping a homemade “natural brew” treatment for the coronavirus. Maduro complained he was being censored by the company. The far right in American politics has been particularly active in sowing doubt about the dangers of the coronavirus, prompting Twitter to delete a tweet from Rudy Giuliani that pushed a similar line to that of Bolsonaro overstating hydroxychloroquine’s effectiveness. Fox News’ Laura Ingraham had a similar tweet, praising hydroxychloroquine, removed. The right-wing site the Federalist has also had one of its more cockamamie coronavirus tweets deleted.

When it comes to the far-right echo chamber, it’s hard to discern where exactly the seed of an idea is first planted—with the president or elsewhere. But Trump has used his platform to push a number of untested cures.

A great early result from a drug that will start tomorrow in New York and other places! #COVIDー19 https://t.co/4F4Qk4WFtK — Donald J. Trump (@realDonaldTrump) March 23, 2020

HYDROXYCHLOROQUINE & AZITHROMYCIN, taken together, have a real chance to be one of the biggest game changers in the history of medicine. The FDA has moved mountains - Thank You! Hopefully they will BOTH (H works better with A, International Journal of Antimicrobial Agents)..... — Donald J. Trump (@realDonaldTrump) March 21, 2020

Twitter has not yet used its oversight powers to rein in potential misinformation spewing from the president of the United States, but it might only be a matter of time.