The anti-parasitic drug ivermectin, which has surged in popularity as an alternative treatment for Covid-19 despite a lack of strong research to back it up, showed no sign of alleviating the disease, according to results of a large clinical trial published on Wednesday.

The study, which compared more than 1,300 people infected with the coronavirus in Brazil who received either ivermectin or a placebo, effectively ruled out the drug as a treatment for Covid, the study’s authors said.

“There’s really no sign of any benefit,” said Dr. David Boulware, an infectious-disease expert at the University of Minnesota.

The researchers shared a summary of these results in August during an online presentation hosted by the National Institutes of Health, but the full data set had not been published until now in The New England Journal of Medicine.