The use of the antiparasitic drug ivermectin could lead to “large reductions” in COVID-19 deaths and may have a “significant impact” on the pandemic globally, according to a recent pre-print review based on peer-reviewed studies.

For the study (pdf), published June 17 in the American Journal of Therapeutics, a group of scientists reviewed the clinical trial use of ivermectin, which has antiviral and anti-inflammatory properties, in 24 randomized controlled trials involving just more than 3,400 participants. The researchers sought to assess the efficacy of ivermectin in reducing infection or mortality in people with COVID-19 or at high risk of getting it.

Using multiple methods of sequential analysis, the researchers concluded with a moderate level of confidence that the drug reduced the risk of death in COVID-19 patients by an average of 62 percent, at a 95 percent confidence interval of 0.19–0.79, in a sample of 2,438 patients.

Among hospitalized COVID-19 patients, the risk of death was found to be 2.3 percent among those treated with the drug, compared to 7.8 percent for those who weren’t, according to the review.

“Moderate-certainty evidence finds that large reductions in COVID-19 deaths are possible using ivermectin. Using ivermectin early in the clinical course may reduce numbers progressing to severe disease,” the authors wrote.

Since the start of the pandemic, both observational and randomized studies have evaluated ivermectin as a treatment for, and as prevention against, COVID-19 infection.

“A review by the Front Line COVID-19 Critical Care Alliance summarized findings from 27 studies on the effects of ivermectin for the prevention and treatment of COVID-19 infection, concluding that ivermectin ‘demonstrates a strong signal of therapeutic efficacy’ against COVID-19,” the researchers wrote, referring to one recent review, which was based on data from both peer-reviewed studies and pre-print manuscripts.

They cited another recent review that concluded that ivermectin reduced deaths by as much as 75 percent, while noting that neither the National Institutes of Health in the United States nor the World Health Organization (WHO) has recommended the use of ivermectin outside clinical trials for use against COVID-19.

The Food and Drug Administration (FDA), in a note on “Why You Should Not Use Ivermectin to Treat or Prevent COVID-19,” warns that it has received “multiple reports of patients who have required medical support and been hospitalized after self-medicating with ivermectin intended for horses.”

“Using any treatment for COVID-19 that’s not approved or authorized by the FDA, unless part of a clinical trial, can cause serious harm,” the FDA said in the note, adding that it hasn’t reviewed data to support the use of ivermectin in COVID-19 patients.

The WHO said in March that “the current evidence on the use of ivermectin to treat COVID-19 patients is inconclusive” and that, until more data becomes available, the agency recommends that “the drug only be used within clinical trials.”

The authors of the efficacy study argued, however, that the drug has an “established safety profile through decades of use” and “could play a critical role in suppressing or even ending the SARS-CoV2 pandemic.”

“The apparent safety and low cost suggest that ivermectin is likely to have a significant impact on the SARS-CoV-2 pandemic globally,” they wrote in the study abstract.

The authors noted in their publication that all the studies on which they based their conclusions have been peer-reviewed.