The world continues to face a life-threatening viral pandemic. The virus underlying the Coronavirus Disease 2019 (COVID-19), Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has caused over 98 million confirmed cases and 2.2 million deaths since January 2020. Although the most recent respiratory viral pandemic swept the globe only a decade ago, the way science operates and responds to current events has experienced a cultural shift in the interim. The scientific community has responded rapidly to the COVID-19 pandemic, releasing over 125,000 COVID-19–related scientific articles within 10 months of the first confirmed case, of which more than 30,000 were hosted by preprint servers. We focused our analysis on bioRxiv and medRxiv, 2 growing preprint servers for biomedical research, investigating the attributes of COVID-19 preprints, their access and usage rates, as well as characteristics of their propagation on online platforms. Our data provide evidence for increased scientific and public engagement with preprints related to COVID-19 (COVID-19 preprints are accessed more, cited more, and shared more on various online platforms than non-COVID-19 preprints), as well as changes in the use of preprints by journalists and policymakers. We also find evidence for changes in preprinting and publishing behaviour: COVID-19 preprints are shorter and reviewed faster. Our results highlight the unprecedented role of preprints and preprint servers in the dissemination of COVID-19 science and the impact of the pandemic on the scientific communication landscape.

25The world continues to face an ongoing viral pandemic that presents a serious threat to human 26 health. The virus underlying the COVID-19 disease, SARS-CoV-2, has caused over 3.2 million confirmed 27 cases and 220,000 deaths between January and April 2020. Although the last pandemic of respiratory 28 disease of viral origin swept the globe only a decade ago, the way science operates and responds to 29 current events has experienced a paradigm shift in the interim. The scientific community has 30 responded rapidly to the COVID-19 pandemic, releasing over 16,000 COVID-19 related scientific 31 articles within 4 months of the first confirmed case, of which at least 6,000 were hosted by preprint 32 servers. We focused our analysis on bioRxiv and medRxiv, two growing preprint servers for biomedical 33 research, investigating the attributes of COVID-19 preprints, their access and usage rates, 34 characteristics of their sharing on online platforms, and the relationship between preprints and their 35 published articles. Our data provides evidence for increased scientific and public engagement (COVID-36 19 preprints are accessed and distributed at least 15 times more than non-COVID-19 preprints) and 37 changes in journalistic practice with reference to preprints. We also find evidence for changes in 38 preprinting and publishing behaviour: COVID-19 preprints are shorter, with fewer panels and tables, 39 and reviewed faster. Our results highlight the unprecedented role of preprints and preprint servers in 40 the dissemination of COVID-19 science, and the likely long-term impact of the pandemic on the 41 scientific publishing landscape. 42 43 44 45 46 47 48 49 50 51 52 53 54The first quarter of 2020 has been defined by the COVID-19 outbreak, which has escalated to 55 pandemic status, and caused over 3.2 million cases and 220,000 deaths within 4 months of the first 56 reported case [1,2]. The causative pathogen was rapidly identified as a novel virus within the family 57Coronaviridae and was named severe acute respiratory syndrome coronavirus 2 (or 'SARS-CoV-2') [3]. 58 Although multiple coronaviruses are ubiquitous among humans and cause only mild disease, 59 epidemics of newly emerging coronaviruses were previously observed in SARS coronavirus in 2002 [4] 60 and Middle East respiratory syndrome (MERS) coronavirus in 2012 [5]. The unprecedented extent and 61 rate of spread of COVID-19 has created a critical global health emergency and academic communities 62 have raced to actively respond through research developments. 63 Research developments have traditionally been communicated via published journal articles or 64 conference presentations. Traditional scientific publishing involves the submission of manuscripts to 65 an individual journal, which then organises peer review. Authors often conduct additional experiments 66or analyses to address the reviewers' concerns in one or more revisions. Even after this lengthy 67 process is concluded, almost half of submissions are rejected and require re-submission to a different ...

RNA viruses are a major threat to human health. Here, based on extensive literature searches carried out over a period of 18 years, we provide a catalogue of all 214 known human-infective RNA virus species. We link these viruses to metadata for a number of traits that influence their epidemiology, including the date of the first report of human infection, transmissibility in human populations, transmission route(s) and host range. This database can be used in comparative studies of human-infective RNA viruses to identify the characteristics of viruses most likely to pose the greatest public health threat, both now and in the future.