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Preprints and the Media: A change to how PLOS handles press for papers previously posted as preprints

This post was written by Beth Baker, PLOS’ Senior Media Relations Manager.


PLOS actively encourages the posting of preprints – please see for all the ways authors can engage. Posting of preprints and discussion of preprints will never affect editorial decisions to publish work in a PLOS journal.

From today, articles accepted at PLOS journals that were previously posted as a preprint will be under a press embargo which lifts upon publication. This alters our prior practice of not applying an embargo to articles that were previously posted as a preprint and means that we will be applying a consistent press embargo to all articles published at PLOS. We have made this decision after conducting research revealing the positive impact of press embargoes for PLOS papers. The change will optimize authors’ opportunities to disseminate their work to the public via the press and will ensure that authors who have posted preprints are not disadvantaged by this choice, nor are authors disincentivized to post preprints.

Open communication of research, and the value of embargoes

PLOS’ press embargo policy is designed to positively impact researchers and to aid the communication of their work. We work to facilitate open communication of research wherever possible. PLOS encourages the discussion of research between scientists at all stages in the publication process. Researchers are free to present and discuss their work for scientific purposes prior to publication. This includes talking about research at conferences and on preprint servers.

While we know that preprints play a crucial role in the efficiency of scientific communication, establishing priority sooner, increasing attention, and opening up the review process to all, we also believe that public attention at scale via the media should focus on the most reliable science: published, peer-reviewed research. Press embargoes continue to be the best tool to facilitate that. 

Embargoes enable authors to achieve accurate, high-quality media coverage which disseminates their peer-reviewed research to non-expert readers. Since our articles are accessible to everyone, everywhere upon publication, our embargoes also ensure that peer-reviewed published articles are accessible to the public when first reported in the media.

Embargoes provide fair and equal access for journalists to allow them time to research their stories and to speak with experts. They give press officers adequate time to coordinate coverage with scientists at their institutions, and give researchers the opportunity to provide comments.

Discussion of research prior to publication, whether in the scientific community or in the media, will never affect editorial decisions to publish work in a PLOS journal. Prior coverage in the media may simply affect if and how PLOS promotes that research at the time of publication.

Background to our research

PLOS partnered with preprint server bioRxiv in May 2018 to help authors opt in to preprints. Soon after, we decided not to embargo for media purposes any published papers which had previously been posted as preprints, believing that embargoes might not be meaningful, necessary, or practical for these papers. Instead, we distributed press releases for such research without embargo at the time of publication, and encouraged institutions to do likewise.

Following implementation of this embargo exception for preprinted papers, we heard concerns from journalists, press officers and the UK Science Media Centre about this policy. Some parties felt that releasing preprinted research without embargo could result in less media coverage, or in lower quality, less accurate coverage, as journalists would race to report on research immediately or decide not to cover it at all. Concerns were also raised that not embargoing preprinted research meant forfeiting a valuable tool to help journalists focus on covering peer-reviewed published research rather than non-peer-reviewed preprints.

PLOS’ media team therefore investigated the claim that non-embargoed preprinted papers received less media coverage.

What we researched and what we found

We took all the preprinted papers we’d press released without embargo between October 1, 2018 (when we introduced the policy) and September 11, 2019 and paired each with a paper we’d press released under embargo that published at around the same time. Each paired paper was from the same journal as the preprinted paper, and for our multidisciplinary journal PLOS ONE, we also ensured the paired paper was in the same broad scientific area.

We examined the amount of media coverage each paper had received by measuring the number of mentions of the paper in the media, using media intelligence software Meltwater. We used paired t tests to assess if differences found were statistically significant. 

We found that the preprinted papers press released without embargo received significantly less media coverage than the paired papers press released under embargo. This was true both in terms of total media mentions (74.60 more media mentions (19.27 vs 93.87); 95% CI: 14.07 – 135.13) and in terms of media mentions in the highest profile outlets (1.47 fewer high profile mentions (0.07 vs 1.53); 95% CI: 0.55 – 2.39). We note that our sample size was small, comprising 30 preprinted papers press released without embargo and 30 paired papers, and we only examined two broad measures of media attention. However, these results support the anecdotes we had previously heard.

How we are reacting

Our research indicates that embargoed papers receive more media coverage, including in the most high-profile news outlets, than papers which are not embargoed. A practice of not embargoing papers previously posted as preprints therefore risked disadvantaging authors who posted preprints, and/or disincentivizing the posting of preprints, which PLOS actively encourages. We have decided to change our practice to treat all our authors equally, and to maximize authors’ opportunities to work with the press to disseminate their work to the public.

From today, all PLOS publications promoted to the press will be embargoed until the time of publication. We believe that this change will enable all our authors to reap the benefits of the embargo system – whether or not they have previously posted preprints – and will facilitate continued high-quality science communication to the public.

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