The World Health Organization warned Thursday that the antiviral drug remdesivir fails to prevent deaths among COVID-19 patients. The WHO’s conclusion is based on a study of more than 11,000 patients. It follows smaller, less rigorous studies that found the drug can cut the number of days COVID-19 patients are hospitalized.

Remdesivir has been routinely administered to COVID-19 patients in the United States since May, when the FDA granted the drug emergency use authorization. It was one of several drugs administered to President Trump as he battled a COVID-19 infection earlier this month.