Ivermectin, a controversial antiparasitic drug that has been touted as a potential treatment for COVID-19, does not shorten recovery time in people with mild cases of the disease, according to a randomized controlled trial published Thursday in the scientific journal JAMA.
Ivermectin is often used to treat parasitic worms in both humans and animals, but scientific evidence of its efficacy against coronavirus is very limited. Some studies have indicated that the drug can prevent various viruses from replicating in cells. And last year researchers in Australia found that, in high doses, in cell cultures, ivermectin suppressed SARS-CoV-2, the virus that causes covid.
These findings encouraged the use of the drug against COVID-19, especially in Latin America.
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–“Ivermectin is currently being used widely,” said Eduardo López Medina, a physician and researcher at the Center for Pediatric Infectious Diseases in Cali, Colombia, who led the new trial. “In many countries in the Americas and in other parts of the world it is part of the national guidelines for the treatment of covid.”
But the drug has caused division. Although some scientists believe it has potential, others suspect that extremely high and possibly dangerous doses are required to effectively inhibit the coronavirus. Health officials also fear that people desperate for coronavirus treatments may take versions of the drug that have been formulated for pets, as it is regularly used to prevent heartworm in dogs.
“There have been many opposing opinions on this, sometimes extremely opposing opinions,” said Carlos Chaccour, a researcher at the Barcelona Institute for Global Health who was not involved in the study. “I think it has become another hydroxychloroquine.”
But neither its defenders nor its critics have had much hard data to support their views. There are few well-controlled trials of the drug’s effectiveness against COVID-19, although more are expected in the coming months. And the treatment guidelines from the U.S. National Institutes of Health advise that not enough evidence “To recommend or discourage” the use of the drug in COVID-19 patients.
In the new study, López Medina and his colleagues randomly assigned more than 400 people who had recently developed mild COVID-19 symptoms to take a five-day regimen of ivermectin or placebo. They found that covid symptoms lasted about 10 days in people who received the drug, compared to 12 days for those who received the placebo, a statistically insignificant difference.
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–The new trial adds much-needed clinical data to the debate on the use of ivermectin as a treatment for COVID-19, said Regina Rabinovich, a physician and global health researcher at the Harvard TH Chan School of Public Health, who was not involved in the the study.
But he noted that the trial was relatively small and does not answer the most pressing clinical question, which is whether ivermectin is capable of preventing serious illness or death. “The duration of symptoms may not be the most important clinical or public health parameter,” he said.
The researchers found that seven patients in the placebo group deteriorated after participating in the trial compared to four in the ivermectin group, but the numbers were too small to reach a meaningful conclusion.
“There was a small signal there, and it would be interesting to see if that signal that we saw is real or not,” said López Medina. “But that would have to be answered in a larger trial.”
López Medina also commented that the study population was relatively young and healthy, with an average age of 37 years and few of the comorbidities that can make COVID-19 more dangerous.
Larger trials are currently underway, which could provide more definitive answers, said Rabinovich, who commented that she was “totally neutral” about the potential usefulness of ivermectin. “I just want data because there is great chaos in the field.”
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