A complete draft of a research paper that is shared publicly, before it has been peer-reviewed.
Peer review can take many months and in a global health emergency such as the COVID-19 pandemic, there is a lot of pressure on researchers to share their research findings. To speed up the process authors have been sharing their manuscripts or preprints, ahead of peer review and approval, with other researchers, allowing for quick collaboration. medRxiv https://www.medrxiv.org is a preprint server for health sciences.
Preprints can be changed or retracted, following peer review. In May 2020, a preprint said that a mutated version of the SARS-CoV-2 called D614G was “more transmissible” and was of “urgent concern”. The preprint was tweeted about 7000 times and picked up by 417 news outlets. The peer-reviewed version published later in the journal called Cell clarified that this was a laboratory study and there was no evidence that the D614G mutation was “more transmissible” among people.
Retraction Watch is a website that tracks the research articles that have had to be retracted by authors. https://retractionwatch.com/retracted-coronavirus-covid-19-papers/
TIP: Approach preprints with caution, as they may be a source of incomplete information or misinformation. Journalists reporting on preprints need to explain to readers that the article has not yet been peer-reviewed and that the findings are preliminary, could change significantly, or even be finally rejected.