All of the social media sites have made explicit that they see misinformation about coronavirus as belonging to a specific category of post, which will attract more strict censure than other posts that break its rules, even those that propagate falsehoods about other issues. As such, the decision by all three sites to remove the recent remarks by Mr Trump may simply be a result of those specific policies.

Both sites have in the past appeared to give the president extra leeway within their rules, because of his high-profile and the newsworthy nature of his posts. As such, they may have been expected to take a similar tactic with coronavirus posts, but some of the sites have already indicated that they will treat Mr Trump’s posts on the issue more critically than they might with other topics.

via Trump Facebook and Twitter posts deleted: Why social networks removed ‘harmful’ coronavirus posts – but might not launch broader crackdown | The Independent