Preprints have moved from a niche practice in physics and computer science to an increasingly common part of medical research dissemination, accelerated in large part by the COVID-19 pandemic. But preprints occupy a fundamentally different position than peer-reviewed publications, and understanding that distinction matters both for researchers deciding whether to post one and for readers deciding how much to trust one.
What Is a Preprint?
A preprint is a complete draft of a research manuscript that is shared publicly — usually via a dedicated server such as medRxiv or bioRxiv — before it has undergone formal peer review. It allows researchers to share findings immediately, establish priority on a discovery, and gather early feedback from the broader research community, all while a manuscript is simultaneously (or subsequently) submitted to a peer-reviewed journal.
The Case for Preprints
Speed of Dissemination
Traditional peer review, even at efficient journals, takes days to weeks. In fast-moving research areas — outbreak response, emerging treatments, urgent public health questions — preprints allow findings to reach clinicians and policymakers far faster than the traditional publication timeline allows.
Open Feedback Before Formal Review
Posting a preprint can surface methodological issues or alternative interpretations from the broader research community before formal peer review even begins, sometimes strengthening the manuscript before it reaches journal reviewers.
Establishing Priority
In competitive research areas, a preprint provides a timestamped, citable record of when a finding was first reported, which can matter for academic credit even before formal publication.
The Risks of Preprints
No Peer Review Means No Quality Filter
This is the central risk, and it cannot be overstated for medical research specifically. A preprint has not been independently evaluated for methodological soundness, statistical validity, or overreach in its conclusions. During the COVID-19 pandemic, several high-profile preprints containing significant methodological flaws received wide media coverage before being corrected or withdrawn — with real potential for public harm given how directly medical findings can influence health decisions.
Media and Public Misinterpretation
Journalists and the public do not always distinguish clearly between a preprint and a peer-reviewed publication. Findings reported from an unreviewed preprint can spread as though they carry the same credibility as a vetted, published study, which is a risk unique to fields — like medicine — where findings directly affect health behavior and clinical decisions.
Clinical Decisions Should Not Rely on Preprints Alone
Because preprints haven’t been vetted by independent experts, they should not, on their own, be treated as a sufficient basis for changing clinical practice or public health policy. Peer review exists precisely to catch the kinds of errors that can have serious downstream consequences in a medical context.
How Preprints Fit Alongside Journal Submission
Most major medical journals, including many operating under standards consistent with the International Committee of Medical Journal Editors (ICMJE) recommendations, now permit prior posting of a preprint without treating it as duplicate publication — provided the preprint is disclosed at submission. Best practice is to:
- Clearly disclose the preprint’s existence and server when submitting to a journal
- Update the preprint record to link to the final peer-reviewed publication once accepted
- Avoid treating preprint posting as a substitute for pursuing formal peer review
Best Practices for Researchers Considering a Preprint
- Be transparent that the work has not yet been peer-reviewed, both in the preprint itself and in any public discussion of it
- Do not present preprint findings with the same certainty you would use for a peer-reviewed publication
- Submit to a peer-reviewed journal in parallel or shortly after, rather than treating the preprint as a final destination
- Be prepared to revise or, if necessary, withdraw the preprint if significant errors are identified
Why Formal Peer Review Still Matters
Preprints and peer-reviewed publication are complementary, not interchangeable. A journal like IJMS, which uses double-blind peer review to independently evaluate methodology, statistical rigor, and the validity of conclusions, provides a level of vetting that a preprint server, by design, does not. For clinical or policy-relevant findings in particular, that independent evaluation is what allows the wider research and clinical community to trust the result.
Final Thoughts
Preprints have a legitimate and growing role in medical research dissemination, particularly for time-sensitive findings — but they are a starting point, not a substitute, for formal peer review. Once your manuscript is ready for that next step, review the IJMS Scope and submit through the Paper Submission page.