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HMSOM Medical Elective: Developing Search Skills

What are Preprints?


Preprints, Postprints & ePrints 

preprint is an article that has not yet undergone peer review, a postprint is an article which has been peer reviewed in preparation for publication in a journal. Both the preprint and postprint may differ from the final published version of an article. Preprints and postprints together are referred to as e-prints or eprints.


Peer Reviewed vs Preprints? 

Peer-reviewed research — the kind that appears in academic journals has undergone a detailed critique by scholars with expertise in the field

A preprint has not been vetted through a formal peer-review process. However, preprints tend to be more complete. Also, preprints submitted to public servers such as the Social Science Research Network and the health sciences server medRxiv get a cursory screening before they’re published online for public view.

Preprints, like academic journal articles, are assigned a Digital Object Identifier, or DOI, and become a permanent part of the scientific record.

Preprints and PubMed

Preprints are complete and public drafts of scientific documents, not yet certified by peer review. These documents ensure that the findings of the research community are widely disseminated, priorities of discoveries are established and they invite feedback and discussion to help improve the work.

Certification by peer review is the key distinction between a preprint and an accepted author manuscript or published article. Many preprints are submitted to journals for publication, and as a result, subsequent versions of the paper may also be made available after peer review. Readers of preprints should be aware that any aspect of the research, including the results and conclusions, may change as a result of peer review (see PMC Disclaimer). Authors may also revise preprints and post updated versions to the preprint server.


Preprints in PubMed

From June 2020 through June 2022, National Library of Medicine, the publisher of PubMed, made more than 3,300 preprints reporting NIH-supported COVID-19 research discoverable in PubMed Central (PMC) and PubMed recognizing that preprint records in PMC and PubMed could provide an avenue for discovery of NIH-supported research prior to journal publication during the ongoing public health emergency. 

In January 2023 the NIH Preprint Pilot launched. This phase expands the scope of preprints included in PMC and PubMed beyond COVID, to include all preprints reporting NIH-funded research and posted to an eligible preprint server.

To ensure that researchers, clinicians, and the public can all easily distinguish between preprints and the journal literature, PMC and PubMed include a prominent green information panel on all preprint records. The text in this panel notes that the article has not yet been peer reviewed and includes a link to more information about the “NIH Preprint Pilot.” A “Preprint” indicator has also been added to the citation metadata and Cite tool, both on the record page and in the search results of PMC and PubMed.

Image of the prominent green information panel that displays on all preprint records. The text in the panel says: This is a preprint. It has not yet been peer reviewed by a journal. The National Library of Medicine is running a pilot to include preprints that result from research funded by NIH in PMC and PubMed.


Preprint Servers

Preprint servers are online repositories which enable you to post this early version of your paper online.

In most academic disciplines preprint servers are now commonly used. Among the most well known are:

  • ArXiv (physical sciences) - (Hosted by Cornell) arXiv is an open-access archive for articles in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics

  • medRxiv (medicine) - (Hosted by Yale, BMJ & Cold Spring Harbor Laboratory) medRxiv accepts preprints of articles covering all aspects of research in the health sciences. 

  • PsyArVix (psychiatry) -  (Hosted by The Society for Improvement of Psychological Science) PsyArVix accepts preprints of articles in the psychological sciences.

  • Research Square (Multidisciplinary)  - (Research Square is a multidisciplinary preprint server that posts research in all scientific areas, including physical, biomedical, and social sciences)

  • SocArXiv (social sciences) -  (Hosted by the University of Maryland) Open archive of the social sciences

  • bioRxiv (biology) - (Hosted by Cold Springs Harbor Laboratory) Open archive of articles in the life sciences 

There are equivalents Pre-Print servers for most research areas.

Keep in mind that preprints have NOT been through a formal peer review process.

The Advantages of Using Preprints in Your Research


Advantages of Preprints

The advantages of preprints can be summarized as: prompt dissemination of outcomes, contributes to free flow of information, increase chances of early feedback and comments, increase number of citations, chances of academic collaborations, make authors enthusiastic, may reduce predatory publishing, increases transparency, may publish negative outcomes and controversies, may receive DOI, link to ORCID, plagiarism check, chance to receive grants and awards, promotion of young researchers, early credit, good place for hypothesis, and early detection of science misconduct


Your manuscript can become available for others to read before the final version of it is published. As publication times can sometimes be lengthy, this gives other researchers a chance to see your work a lot quicker.


The preprint is a public record that you published that research at that time. Your work will likely be assigned a digital object identifier (DOI).

Innovative Research

By making research visible before official publication, researchers with innovative ideas can be suitably credited. The process from finalizing a draft to publishing a peer-reviewed article can be lengthy. Because of this, preprints can help researchers to get results out quicker. This is especially useful if any major delays are experienced during the review process, or if similar research comes out before the publication of full research papers.


Preprints receive their own digital object identifier (DOI), meaning that researchers can easily cite preprints. Publishers often provide “How to Cite” instructions for anybody looking to reference research from preprints. And because preprints are citable, academics can discuss information and results from preprints within their work.

Pre Prints are Screened Before Uploaded to a Server

Preprints  can come in various forms, including as reviews and case reports. And once preprints are submitted for publication, they are subject to certain checks. For example, in all of the reputable Pre Printer Servers, preprints undergo a thorough series of checks to make sure they’re reliable. Most undergo a screening process that includes making sure that basic publication ethics are adhered to, conflicts of interest are disclosed by authors.


Posting your preprint allows other researchers to offer feedback that may help to improve your article before the more formal journal peer review process.

Research impact

The research presented in your preprint will be publicly available for other researchers or practitioners to cite and build upon more quickly.

The Disadvantages of Using Preprints in Your Research

Disadvantages of Preprints

The disadvantages of preprints could be summarized as: lack of peer-review, absence of quality (in controversy), concerns about premature data, media coverage not properly presenting the inherent uncertainty of preprints, risk of double citation (by publishing a peer- reviewed article, the preprint may also be cited), lack of ethical and statistical guidelines, lack of respect for COPE or ICMJE guidelines, breach of intellectual property regulations in some countries, possible harm to health in certain cases, information overload, rush to post low-quality research.

Preprint Reliability

Because preprints aren’t as established yet, it can be difficult to make clear that the information available in preprints isn’t verified in the same way as information in other research articles. As witnessed during the COVID-19 pandemic, this can lead to problems during major health crises.

The pandemic illustrated both the pros and cons of preprints. Due to the novelty and uncertainty of the COVID-19 pandemic, many people were looking to find out more about the science behind it. While preprints helped researchers to share data about the pandemic at a rapid pace, problems arose as many news outlets picked up on the information. The circulation of preliminary findings as facts meant conflicting information was delivered to the public. This led to issues such as misinformation and lack of trust in the science.

These issues can be solved by making clear that preprints haven’t been peer reviewed, and that the research in preprints is therefore less reliable than the information available in other academic publications.

Lack of Acceptance and Publication of Full Papers

Despite being about for around 30 years online, preprints only really took off during the COVID-19 pandemic, when fast-paced research became key. The rise in interest since then has led to considerations of the pros and cons of preprints. And they’re most often distributed over the internet as opposed to in the form of paper copies today, following the trend of most academic publications.

However, there is less space made for preprints across journals. Many publishers don’t accept preprints or have certain stipulations for the research published in preprints. For example, when publishing a preprint, researchers should be mindful that some journals prohibit the republication of research included in preprints. If you have any plans to publish your work with a certain journal, double check that you’ll still be able to do this once you’ve published your preprint.

Will Uploading to a Preprint Server Jeopardize Journal Publication

Can I submit my article to a journal if it’s already uploaded to a preprint server?

If you upload an early version of your article to a non-commercial preprint server, you can subsequently submit to most published journals. Most journal publishers do not consider posting on a preprint server to be duplicate publication and this will not jeopardize consideration for publication. Actually most journal publishers host there own Pre-Print Servers!


Transpose Database - (TRANsparency in Scholarly Publishing for Open Scholarship Evolution) is an initiative to build a database of journal policies. They focus on three areas: open peer review, co-reviewing, and detailed preprinting policies. 


Most journal publishers request once your article is accepted for publication, that you update the preprint to acknowledge that the article has been accepted for publication as follows:

This article has been accepted for publication in [JOURNAL TITLE], published by [Publisher].

After publication you can add the following text to your preprint to encourage others to read and cite the final published version of your article:

“This is an original manuscript of an article published by [Publisher] in [JOURNAL TITLE] on [date of publication], available online:[Article DOI].”