What just happened? Once again, a Donald Trump tweet has been labeled with a fact-check warning by the social network. A post by the president in which he claimed to be "immune" to Covid-19 after being given the all-clear by the White House has been flagged as violating Twitter's rules.

Trump's tweet came soon after a three-night stay in hospital following his positive test for Covid-19. "A total and complete sign off from White House Doctors yesterday. That means I can't get it (immune), and can't give it. Very nice to know!!!," he wrote.

Twitter has an extensive policy when it comes to what information is posted regarding the Coronavirus. This includes requiring the removal of tweets intended to influence others to violate Covid-19 guidance, claims about ineffective/harmful treatments, and ads for unverified treatments and cures.

Trump's message is hidden behind the warning: "This Tweet violated the Twitter Rules about spreading misleading and potentially harmful information related to COVID-19. However, Twitter has determined that it may be in the public's interest for the Tweet to remain accessible."

Back in 2017, Twitter responded to complaints that some of Trump's posts relating to North Korea incited violence by stating they were newsworthy and wouldn't be removed. The company started exploring the idea of labeling similar tweets two years later.

Despite being a prolific user of the platform, Trump has clashed with Twitter on several occasions this year. He said the site was "stifling free speech" in May after his claim about mail-in ballots was labeled with a fact-checking warning. It also flagged his 'racist baby' tweet with a manipulated media label, and last week saw both Facebook and Twitter take action against his post that suggested seasonal flu is deadlier than Covid-19.