A study that touted the anti-malaria drug hydroxychloroquine as an effective treatment for the novel coronavirus has drawn new concern from the group that publishes the journal in which the work first appeared.

In a statement last week, the International Society of Antimicrobial Chemotherapy (ISAC) said the study in question did not meet its standard—but did not go into many details as to why.

“ISAC shares the concerns regarding the above article published recently in the International Journal of Antimicrobial Agents (IJAA). The ISAC Board believes the article does not meet the Society’s expected standard, especially relating to the lack of better explanations of the inclusion criteria and the triage of patients to ensure patient safety,” the notice read. The notice was first reported by Retraction Watch.

ISAC’s notice acknowledged some criticisms of the study posted online regarding its potentially rushed peer-review. However, the society said the study’s process did “adhere to the industry’s peer-review rules.”

The study, led by the University of Marseille’s Didier Raoult, concluded that hydroxychloroquine treatment was “significantly associated” in reducing and eliminating the virus in COVID-19 patients. The addition of azithromycin to the treatment led to it being “significantly more efficient for virus elimination.”

The study reported testing 36 French COVID-19 patients in March, with the majority of them showing upper respiratory tract infection symptoms. They received 600mg of hydroxychloroquine daily, and were tested every day via nasal swabs. The addition of azithromycin to the treatment depended on patients’ “clinical presentation.”

President Donald Trump has publicly touted hydroxychloroquine as a potential cure for COVID-19, telling reporters Sunday that the drug was “great” and there were “signs that it works on this, some very strong signs.” He’s also called for the Indian prime minister to release more of the drug to the U.S. just as India placed a ban on the export of the drug.

According to CNN, the president also lauded the azithromycin addition to the hydroxychloroquine treatment, claiming azithromycin would “kill certain things that you don’t want living within your body.”

Trump started publicly mentioning hydroxychloroquine after Fox News guests and hosts began mentioning it on-air last month. On March 16, a guest on The Ingraham Angle specifically mentioned Raoult’s study days before it published.

“Within a matter of six days, the patients taking hydroxychloroquine tested negative for coronavirus, COVID-19,” Gregory Rigano—identified as a co-author of a study on chloroquine—told host Laura Ingraham. “This is a well-controlled study.”

Mehmet Oz, the TV doctor who has been advising Trump administration officials on coronavirus-related issues, also has publicly praised the study on Fox–calling Raoult a “well-respected French physician who’s done a lot of this work” and stating that the study’s “statistical significance” needed to be taken seriously.

“If it takes me 30,000 patients to show a difference, is that better than showing a difference in 62 patients? If a small trial demonstrates statistically significant differences, you should respect it,” Oz told host Brian Kilmede on Monday. “At least pay attention to it.”