Interactive cumulative step curves of preprints addressing the COVID-19 epidemic posted to A) bioRxiv, B) medRxiv and C) arXiv preprint servers over time. Data points display individual preprint information upon mouseover and hyperlink to the preprint upon click. Search terms used covered "coronavirus", "coronaviruses", "ncov", "SARS-CoV-2", and "COVID-19". Colours denote categorisation from preprint metadata, as defined and classified by each preprint server ('bio' - bioRxiv, 'med' - medRxiv, 'arx' - arXiv).