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. 

At that point, the journal asked the university to investigate, a spokesperson for The Lancet Group told us by email: 

The editors of The Lancet Regional Health – Americas asked McMaster University for an investigation into the analyses from the TOGETHER trial in January 2024. We received the final report from McMaster University on 21st April 2025 which stated the hearing committee concluded the author did not breach the University’s research integrity policy. We are now working with the authors on the best way to correct the record and will keep you updated.

The university’s final report came six days after we contacted McMaster about the paper. Jennifer Stranges, communications and media relations manager at McMaster, told us on April 15: “Information about concerns or potential investigative processes are confidential, and anything to be released to the public would be done so at the completion of the process.” 

“So a year and 3 months just for them to agree that we weren’t conducting any malfeasance,” Mills said. He said he expects the correction will be published “within the next few weeks.” 

Stranges did not reply to our question on why the investigation took so long. 

McMaster made headlines a few years ago for its investigation into behavioral ecologist Jonathan Pruitt. Questions about Pruitt’s work garnered public attention in January 2020 and were reported to the university around the same time. The university found Pruitt “engaged in data falsification and fabrication in several papers,” all before joining the faculty, according to a May 2023 statement from the university.

The TOGETHER trial was a multi-arm clinical trial at 13 clinics in Brazil set up to test different drugs in people with COVID-19 at high risk for complications. The metformin arm of the trial started treating patients in January 2021, and the safety committee recommended halting it that April, as the drug was not affecting outcomes. 

Other arms of the trial tested ivermectin, hydroxychloroquine and fluvoxamine, among other drugs.

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