Now, they have turned their attention to junk news about the COVID-19 crisis, helping social-media platforms move more quickly to dispel and discourage rumors, misinformation, and conspiracy theories.
By criticising democracies as corrupt and incompetent, praising authoritarian leaders' global leadership, and promoting conspiracy theories about the origins of the coronavirus and the motives of international health agencies, they are trying to shape - or at least muddy - the global narrative as much as possible.
By analysing a large sample of health-related COVID-19 lies, we found that one in five can be sourced to politicians, celebrities, and prominent public figures, and that a huge proportion of the misinformation is being propelled by media agencies controlled by authoritarian governments.
A global community of fact checkers that came together after the United Kingdom's Brexit debate and the U.S. presidential election in 2016 has rapidly pivoted to checking health information.
The dissemination of politicised health messages is especially dangerous, as are attacks on credible public agencies and trustworthy, professional news organisations.