Microbiome company CEO who linked COVID vaccine to bacterial decline now has four retractions

A gastroenterologist and microbiome researcher who has promoted hydroxychloroquine and ivermectin as COVID treatments has lost a paper after a sleuth reported differences between the article and the registered protocol of the clinical trial it purported to describe. 

The retracted article, on detecting SARS-CoV-2 in fecal samples, was published in Gut Pathogens in January 2021. It marks the fourth retraction for study coauthor Sabine Hazan.

Hazan is founder and CEO of ProgenaBiome, a laboratory in Ventura, Calif., advertising clinical trials exploring the role of the gut microbiome in conditions including autism and Alzheimer’s disease, as well as COVID. She is also CEO of Ventura Clinical Trials, which lists dozens of pharmaceutical and biotech companies among its clients.  

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Do men or women retract more often? A new study weighs in

The male/female retraction ratio for Zheng and colleagues’ dataset showed that male first authors have a higher retraction rate than females.  Source: E-T Zheng et al/J of Informetrics 2025

When you look at retracted papers, you find more men than women among the authors. But more papers are authored by men than women overall. A recent study comparing retraction rates, not just absolute numbers, among first and corresponding authors confirms that men retract disproportionally more papers than women. 

The paper, published May 20 in the Journal of Informetrics, is the first large-scale study using the ratio of men’s and women’s retraction rates, said study coauthor Er-Te Zheng, a data scientist at The University of Sheffield. The researchers also analyzed gender differences in retractions across scientific disciplines and countries.

Zheng and his colleagues examined papers from a database of over 25 million articles published from 2008 to 2023, about 22,000 of which were retracted. They collected the reasons for retraction from the Retraction Watch Database, and used several software tools to infer each author’s gender based on name and affiliated country. 

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Slovak science academy ‘strictly condemns’ government official’s paper on mRNA vaccines

Peter Kotlár

Slovakia’s national science academy has issued a strong critique of a paper on mRNA vaccines coauthored by a member of the country’s parliament. The group called the work “insufficiently detailed” and “lacking controls,” with data that “may be misleading” and conclusions “not supported by sufficiently robust data.” 

Peter Kotlár, the paper’s second author, is an orthopedist and represents the far-right Slovak National Party. He is also the commissioner for a review of resource management during the COVID-19 pandemic for the government of populist prime minister Robert Fico, himself known for questioning the science around COVID-19.

The paper appeared May 13 in the Journal of Angiology and Vascular Surgery, published by Herald Scholarly Open Access. “The journal in which the study of Peter Kotlár was published, is not evidenced in databases Web Of Science and Scopus,” a spokesperson for the Slovak Academy of Sciences, Monika Tináková, told us. The issues with the paper reflect “the fact that the journal in which it was published is classified as a so-called predatory journal,” the statement, issued last month, reads. 

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Springer Nature psycholinguistics journal retracts over a dozen articles for authorship, peer review issues

A journal has retracted 16 papers after a whistleblower flagged it for “irregularities” in peer review, among other concerns. 

The Journal of Psycholinguistic Research, a Springer Nature title, published the papers between 2021 and 2024. The articles covered research ranging from studies of the work of Haruki Murakami and Kazakh literature to English reading fluency and the teaching competence of parents of children with cochlear implants.

Thirteen of the 16 articles have been cited one to five times, according to Clarivate’s Web of Science; one article has been cited 19 times, the highest of the bunch. 

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‘More of the same’: Journals, trade website refuse to correct critiques of book on Alzheimer’s fraud

Amyloid-beta plaques (brown) and tau protein tangles (blue). Credit: National Institute on Aging/NIH

Investigative journalist Charles Piller’s latest book, Doctored: Fraud, Arrogance, and Tragedy in the Quest to Cure Alzheimer’s, came out in February. It details the work of Matthew Schrag, a neurologist at Vanderbilt University in Nashville, Tenn., and other sleuths who uncovered evidence of problems in hundreds of research papers about the neurologic condition. 

Most reviews and coverage have been positive, Piller said. But some Alzheimer’s researchers have criticized the book in reviews published in JAMA, The Lancet Neurology, and the website Alzforum, which hosts news and commentary on Alzheimer’s research. 

Piller and Schrag say they respect that others are entitled to their opinions, but expressed concern that some of these reviews contain inaccuracies that downplay their findings. And the journals and Alzforum have refused to publish responses they submitted or make corrections they requested. 

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How do retractions impact researchers’ career paths and collaborations?

About 46% of authors leave their publishing careers around the time of a retraction, a new study has found.
SA Memon et al/Nat Hum Behav 2025

Several studies have tackled the issue of what effect a retracted paper has on a scientist’s reputation and publication record. The answer is, by and large, it depends: The contribution the researcher made on the paper, their career stage, the field of study and the reason for the retraction all play a role.

Three researchers from New York University’s campus in Abu Dhabi wanted to  better understand how a retraction affects a scientist’s career trajectory and future collaborations. Using the Retraction Watch Database, they looked at papers retracted between 1990 and 2015, and merged that data with Microsoft Academic Graph to generate information on researchers’ pre- and post-retraction publication patterns, as well as their collaboration networks. They also looked at Altmetric scores of retractions to factor in the attention a retraction got.

From that data, they extrapolated if and when researchers with retracted papers left scientific publishing, and looked for trends in researchers’ collaboration networks before and after the retraction.

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Journal investigating placebo effect study following Retraction Watch inquiry

An Elsevier journal is investigating a paper by a controversial author after a Retraction Watch inquiry about the article. The article concluded that “placebo effects have a significant impact on observed outcomes” in both placebo and treatment groups in clinical trials. 

The senior author of the paper is Harald Walach, whose name may be familiar. In one paper, now retracted, Walach and his coauthors claimed COVID-19 vaccines killed two people for every three deaths they prevented. In a different paper, also retracted, Walach and his colleagues claimed children’s masks trap carbon dioxide; they later republished the article in a different journal. He lost two papers and a university affiliation in 2021. 

One of his latest papers, “Treatment effects in pharmacological clinical randomized controlled trials are mainly due to placebo,” appeared online December 27 in the Journal of Clinical Epidemiology

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Why has it taken more than a year to correct a COVID-19 paper?

A correction to a clinical trial on a potential treatment for COVID-19 has taken more than a year — and counting — to get published. In the meantime, the article remains marked with an expression of concern that appeared in February 2024. 

The Lancet Regional Health–Americas published the study, a randomized clinical trial of the effect of metformin on hospitalization rates among COVID-19 patients, in December 2021. It has been cited 36 times, according to Clarivate’s Web of Science, 12 of those since the publication of the expression of concern.

In December 2023, the authors “identified small errors in the statistical analysis primary outcome,” corresponding author Edward Mills, a health research methods professor at McMaster University, in Hamilton, Ontario, told Retraction Watch. “We immediately re-ran the analysis and submitted as an erratum,” he said. 

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Do men or women retract more? A study found the answer is … complicated 

A new study compares retraction rates between men and women.
Pexels

Longtime Retraction Watch readers know the scientists on our Leaderboard have changed over the years. But one characteristic has remained relatively constant: There are few women on that list – in fact, never rarely more than one at a time.

So when a recent paper dove into whether retraction rates vary by the gender of the authors, we were curious what the authors found.

The team, from Sorbonne Study Group on Methods of Sociological Analysis (GEMASS) in Paris, sampled 1 million articles from the OpenAlex database, then referenced the Retraction Watch database to compare against their sample. 

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COVID-19 vaccine myocarditis paper raises questions about what earns post-publication peer review

On March 7, a Sage journal published an expression of concern for an article on cases of myocarditis in people who had received a COVID-19 vaccine. 

“The Editor and the publisher were alerted to potential issues with the research methodology and conclusions and author conflicts of interest” and had undertaken an investigation of the article, the notice stated. According to one of the authors, the investigation involved two new peer reviews of the paper. 

We’ve reported on many cases of authors disagreeing with retractions other publishers issued after conducting post-publication review processes. The papers often involve hot-button issues – pesticide poisoning, the effect of vaping on smoking rates, an estimation of deaths from the use of hydroxychloroquine early in the COVID-19 pandemic, and President Trump’s role in spreading vaccine misinformation on Twitter before the company suspended his account.  

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