But the social media giants are straining to make real-time judgment calls on borderline content, having to quickly figure out what counts as a conspiracy and what’s just speculation at a time in politics when anything seems possible. As they grapple with that task, voters could be inundated with a new wave of misinformation just weeks ahead of the election.

There are posts circulating, for example, that — without evidence — raise doubts about whether Trump is being honest about his diagnosis or that speculate that the episode is part of a plan for Trump to retreat before declaring war on his political enemies buried deep inside government…

Facebook, the world’s largest social network, stood up an ad hoc “operations center” — like the ones built around presidential debates and primary election contests — to tackle the Trump-Covid news well before the work day started in Washington, spokesperson Andy Stone said.

Some calls are easy, the companies say. Posts hoping President Trump will lose his life to the virus are banned under the major platforms’ restrictions on bullying or hateful conduct.