According to Guy Rosen, vice president of integrity at Facebook, the issue was due to a bug in an anti-spam system. It did not have to do with the fact that Facebook is leaning more heavily on its machine learning systems for content moderation, a strategy Google has also resorted to. Apparently, the bug removed non-coronavirus posts, too. All of which have been restored.

We're on this - this is a bug in an anti-spam system, unrelated to any changes in our content moderator workforce. We're in the process of fixing and bringing all these posts back. More soon. — Guy Rosen (@guyro) March 17, 2020

As the pandemic continues, fighting misinformation will be an even bigger challenge than it normally is. Facebook has already offered free ads to reputable sources like the World Health Organization and banned ads promoting false "cures." Google has a multi-faceted approach, and Apple is rejecting coronavirus apps to limit misinformation. While these efforts are necessary, they could be undermined by bugs like the one Facebook just encountered.