BackgroundThe epidemic of COVID-19 disease originating in Wuhan, China in December 2019 has continued to spread, with global outbreak size currently estimated at 372,757 cases (of which 81,747 occurred within China) \cite{who_novel_2020-2}. Initial concerns about cryptic localised spread have materialised, as human-to-human transmission is confirmed to have occurred within 110 countries \cite{who_novel_2020-2}, with the largest secondary outbreaks since February in Western Europe, the USA, and Iran. The causative virus was identified as a novel betacoronavirus \citep{zhu_novel_2020} and named as SARS-CoV-2 on the 11th February \citep{gorbalenya_severe_2020}.While scientific knowledge surrounding the current public health emergency continues to advance on a daily basis, an important driver in coordinating a research response to the outbreak has been the use of preprints. Uploading unreviewed manuscripts to open-access repositories as preprints can offer immediate knowledge sharing without restrictions from potentially lengthy journal submission and publication processes. Preprint usage can also bring wider benefits to academic research, including further citation potential and a more equitable system of credit for early career researchers \citep{sarabipour_value_2019}. Growth in preprint repositories has surged in the last five years \cite{asapbio_biology_2019}, becoming a more everyday element of scientific literature access and academic culture \citep*{abdill_tracking_2019}, with 31% of authors surveyed in 2016 reporting they have posted at least one preprint \citep{asapbio_survey_2016}. While posting preprints has been generally encouraged across life sciences \citep{desjardins-proulx_case_2013,berg_preprints_2016}, there have also been specific calls for better open platform science during active outbreaks \citep{yozwiak_data_2015}, in order to improve the potential for research to guide timely public health responses. Here I sought to a) review and characterise the use of academic preprints in research addressing the COVID-19 outbreak, and b) quantify their growth in comparison to previous infectious disease outbreaks.