Ivermectin Doesn't Help Treat COVID-19, Large Study Finds

Carolyn Crist

March 31, 2022

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Ivermectin, an anti-parasitic drug that became popular as an alternative treatment for COVID-19, showed no signs of quelling the disease or reducing patients' risk of hospitalization, according to results from a large clinical trial published in The New England Journal of Medicine.

The findings pretty much rule out the drug as a treatment for COVID-19, the study authors wrote.

"There's really no sign of any benefit," David Boulware, MD, one of the co-authors and an infectious disease specialist at the University of Minnesota, told The New York Times.

The researchers shared a summary of the results in August 2021 during an online presentation hosted by the National Institutes of Health. The full data hadn't been published until now.

"Now that people can dive into the details and the data, hopefully that will steer the majority of doctors away from ivermectin towards other therapies," Boulware said.

In the trial, the research team compared more than 1,350 people infected with the coronavirus in Brazil who received either ivermectin or a placebo as treatment.

Between March and August 2021, 679 patients received a daily dose of ivermectin over the course of 3 days. The researchers found that ivermectin didn't reduce the risk that people with COVID-19 would be hospitalized or go to an emergency room within 28 days after treatment.

In addition, the researchers looked at particular groups to understand if some patients benefited for some reason, such as taking ivermectin sooner after testing positive for COVID-19. But those who took the drug during the first 3 days after a positive coronavirus test ended up doing worse than those in the placebo group. The drug also didn't help patients recover sooner.

The researchers found "no important effects" of treatment with ivermectin on the number of days people spent in the hospital, the number of days hospitalized people needed mechanical ventilation, or the risk of death, they wrote.

Ivermectin has become a controversial focal point during the pandemic.

For decades, the drug has been widely used to treat parasitic infections. At the beginning of the pandemic, researchers checked thousands of existing drugs against the coronavirus to determine if a potential treatment already existed. Laboratory experiments on cells suggested that ivermectin might work, the Times reported.

But some researchers noted that the experiments worked because a high concentration of ivermectin was used, a much higher dose than would be safe for people. Despite the concerns, some doctors began prescribing ivermectin to patients. After receiving reports of people who needed medical attention, particularly after using formulations intended for livestock, the FDA issued a warning that the drug wasn't approved to be used for COVID-19.

Researchers around the world have done small clinical trials to understand whether ivermectin treats COVID-19, the newspaper reported. At the end of 2020, Andrew Hill, MD, a virologist at the University of Liverpool in England, reviewed the results from 23 trials and concluded that the drug could lower the risk of death from COVID-19. He published the results in July 2021, but later reports found that many of the studies were flawed, and at least one was fraudulent.

Hill retracted his original study and began another analysis, which was published in January 2022. In this review, he and colleagues focused on studies that were least likely to be biased. They found that ivermectin was not helpful.

Recently, Hill and his colleagues ran another analysis using the new data from the Brazil trial, and once again they saw no benefit.

Several clinical trials are still testing ivermectin as a treatment, the Times reported, with results expected in upcoming months. After reviewing the data from the Brazil trial, which tested ivermectin and a variety of other drugs against COVID-19, some infectious disease experts say they'll likely see more of the same — that ivermectin doesn't help people with COVID-19.

"I welcome the results of the other clinical trials and will view them with an open mind," Paul Sax, MD, an infectious disease expert at Brigham and Women's Hospital who has been watching the data on the drug throughout the pandemic, told the newspaper.

"But at some point, it will become a waste of resources to continue studying an unpromising approach," he said.

Sources

The New York Times: "Ivermectin Does Not Reduce Risk of Covid Hospitalization, Large Study Finds."

National Institutes of Health: "August 6, 2021: Early Treatment of COVID-19 with Repurposed Therapies: The TOGETHER Adaptive Platform Trial."

FDA: "Why You Should Not Use Ivermectin to Treat or Prevent COVID-19."

Open Forum Infectious Diseases: "Retracted: Meta-analysis of Randomized Trials of Ivermectin to Treat SARS-CoV-2 Infection," "Ivermectin for COVID-19: Addressing Potential Bias and Medical Fraud."

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