“The coronavirus is a bioweapon”: classifying coronavirus stories on fact-checking sites

The 2020 coronavirus pandemic has heightened the need to flag coronavirus-related misinformation, and fact-checking groups have taken to verifying misinformation on the Internet. We explore stories reported by fact-checking groups PolitiFact, Poynter and Snopes from January to June 2020. We characterise these stories into six clusters, then analyse temporal trends of story validity and the level of agreement across sites. The sites present the same stories 78% of the time, with the highest agreement between Poynter and PolitiFact. We further break down the story clusters into more granular story types by proposing a unique automated method, which can be used to classify diverse story sources in both fact-checked stories and tweets. Our results show story type classification performs best when trained on the same medium, with contextualised BERT vector representations outperforming a Bag-Of-Words classifier.