French medical researcher Didier Raoult is facing renewed questions about his research record after scientists found major ethics concerns in hundreds of papers linked to his former institute.
An international team reviewed work from the Institut Hospitalo Universitaire Méditerranée Infection in Marseille. The team found concerns in 853 papers published by the institute.
Raoult was a co author on 758 of those papers, according to one researcher involved in the review. The findings add to earlier concerns about research practices at the institute.
The review also raises questions about the checks used to protect patients and maintain research standards. The researchers said more work is needed to assess the full impact of the concerns.
Raoult became well known around the world in early 2020. At the time, the Covid pandemic was spreading fast and countries were looking for possible treatments.
His team published a study that said hydroxychloroquine could help treat Covid. The study also looked at the drug when used with azithromycin.
The claim gained wide public attention. Former US President Donald Trump praised the work and called the treatment a possible major medical breakthrough.
Dr Mehmet Oz also praised the study at the time. Oz later became head of the US Centers for Medicare and Medicaid Services.
Oz said he was surprised by the study results. He also said more research was needed and noted that the work was not a large random trial.
Oz later contacted officials in the Trump administration and promoted the research as a possible answer to the pandemic. He also interviewed Raoult during the early months of the crisis.
However, later research did not show that hydroxychloroquine was an effective treatment for Covid. The early Raoult paper was later retracted in 2025 after concerns about its science and ethics.
The study had already gained major influence by that time. It was cited thousands of times and became a major part of the public debate over Covid treatment.
Researchers involved in the new review say the paper also caused wider problems. They said interest in the drug grew sharply and contributed to shortages in some places.
They also argued that the focus on hydroxychloroquine took time and attention away from other possible research. The study later became part of wider claims about vaccines and Covid policy.
The new review looked at 2,674 papers published by the institute between 1994 and 2024. Researchers found several types of ethics concerns across the work.
They said at least 78 papers described human research that appeared not to meet French legal rules. They also found 343 papers where no ethics approval was recorded.
In other cases, researchers said approval may have been given after a study had already started. They also found cases where the same ethics approval appeared to be used for different studies.
The researchers said these findings do not mean every paper was invalid. However, they said the scale of the concerns requires further review.
They called for journals and institutions to check the research record and correct papers where needed. They also said stronger oversight is needed to protect trust in medical research.
The researchers raised questions about Aix Marseille University, which was responsible for oversight of the institute.
The university said it had taken steps after concerns were first raised in 2020. It said it carried out its own review and shared its findings with the proper authorities.
The university also said it worked with scientific publishers and improved its systems for research oversight. It stressed that research ethics and integrity remain key parts of its work.
Raoult retired in 2021. He has defended his research in the past and said he followed the rules for research ethics.
The latest findings show why strong research checks matter, especially during a health crisis. Medical studies can affect treatment choices, public policy and patient safety.
The researchers said their main goal is to improve research standards. They want the scientific record to be checked and corrected when serious problems are found.
The case also shows how quickly medical claims can spread during a crisis. Strong evidence, clear methods and careful review remain vital before any treatment is promoted as a solution.
