A preprint server has withdrawn a study that suggested children vaccinated in the second month of life are more likely to die soon after when compared to those who did not receive the vaccinations.
The paper, posted at Preprints.org last December, was written by Karl Jablonowski and Brian Hooker of Children’s Health Defense, a New Jersey-based nonprofit organization founded by U.S. Secretary of Health and Human Services Robert F. Kennedy Jr. The group is known for anti-vaccination advocacy.
Jablonowski and Hooker conducted their analysis using a dataset provided by the Louisiana Department of Health. It included 1,775 children who died before turning 3 years old between 2013 and 2024 and had a record of being vaccinated. The preprint suggested children who received six recommended vaccinations in the second month of life were more likely to die in their third month compared to those who had not received the vaccinations.
On January 14, Preprints.org, which is run by the Multidisciplinary Digital Publishing Institute (MDPI), withdrew the article. According to the withdrawal notice, the server’s advisory board suggested the paper be removed, and the withdrawal has been communicated to indexing organizations.
Loren Mell, a physician-scientist and clinical investigator at the University of California San Diego who reviewed the paper at our request, said the study has methodological shortcomings.
“There are numerous weaknesses to the scientific conduct of the study,” which “eat into the validity of the conclusions,” Mell said.
Mell took issue with the way the retrospective study selected the data. “There’s a lot of assumptions that are baked into that that you would have to buy to be assured of the validity of their conclusions,” he said. “There’s too many flaws in that type of design.”
Hooker has had two articles on vaccines retracted. One, published and retracted in 2014, suggested the measles-mumps-rubella (MMR) vaccine increased the risk of autism in African American boys. It was retracted for compromised peer review and concerns about the methods and analysis. The other, published in 2015 and retracted in 2017, focused on alleged conflicts of interest in autism research. It was retracted in part for the authors’ failure to disclose conflicts of interest.
After their latest preprint was withdrawn, Jablonowski and Hooker immediately reposted the paper on Zenodo, a repository run by the European Organization for Nuclear Research (CERN).
After being contacted for comment by Retraction Watch, Zenodo added the following disclaimer statement on the article:
Caution: Unverified Contents
Papers and preprints are not peer-reviewed by Zenodo, and must be regarded as preliminary until peer-reviewed by multiple experts in the field. It should not be regarded as conclusive, or reported in news media as established information, as the main claims may not stand the test of scientific scrutiny.
Please note that this preprint was withdrawn from its original publication on preprints.org: https://www.preprints.org/manuscript/202512.1865
Jablonowski and Hooker did not reply to multiple requests for comment, but in January they told The Defender (the newsletter of the Children’s Health Defense):
There are 318 members of the Advisory Board for Preprints. Not a single one of them has published on vaccine safety. Not a single one of them has published on infant mortality. Not a single one of them would have been chosen to peer-review our article. Its retraction, therefore, cannot be a peer-reviewed nor a scientific decision.
We have not attempted to verify these claims.
A CERN spokesperson told us “anyone can upload content to Zenodo, which means that some publications may not fully comply with the rules.”
The spokesperson added, “If a publication is reported, Zenodo will remove it from public access and begin an assessment of the content. After the review, it may either be reinstated or permanently removed, depending on the outcome.”
MDPI public affairs manager Jisuk Kang told us concerns about the paper’s methodology were brought to them along with concerns about the findings being misinterpreted by a general audience.
According to Kang, Preprints.org’s withdrawal policy allows preprints to be removed in “very exceptional circumstances, including situations where the content may be misinterpreted and could pose a potential risk to the public.”
Kang added:
We would like to emphasize that this action does not constitute a judgment on the authors’ intentions, nor does it imply scientific or legal misconduct. Rather, it reflects the preliminary nature of preprints and our responsibility to mitigate the risk of public misinterpretation. We encourage the authors to submit their work to a peer-reviewed journal, where the findings can be formally assessed and appropriately contextualized.
“I think that the paper seemed to be more about advancing a predetermined position as opposed to a good faith scientific inquiry,” Mell told us, referring to the paper as of “dubious scientific value.”
“It’s a completely valid form of censorship,” Mell said, pointing to the preprint’s removal. “I would call it editorial discretion, not censorship.”
“The way this particular article was written, you can tell right out of the gate that these authors have a vested stake in the outcome of their study and a prior bias,” Mell said. “There’s nothing quite as useless as a scientist who’s already made up their mind about a subject.”
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