A study by Duke University's researchers suggests that the antiparasitic drug for humans and horses, ivermectin, is not effective in treating mild to moderate COVID-19 cases.
During the pandemic's peak, ivermectin was praised, especially by vaccine opponents, as a drug to prevent and treat COVID-19. Prescriptions of the medicine skyrocketed from an average of 3,600 before the pandemic to more than 88,000 prescriptions in the week ending August 13, 2021.
The US Food and Drug Administration (FDA) discouraged people from taking medicine that is primarily used in horses but also approved for human use to treat infections caused by certain parasitic worms, head lice, and skin conditions like rosacea.
The American Medical Association (AMA), American Pharmacists Association (APhA), and American Society of Health-System Pharmacists (ASHP) also "strongly opposed" prescribing ivermectin "to prevent or treat COVID-19 outside of a clinical trial."
The study from Duke University, published in the Journal of the American Medical Association (JAMA) on Friday, included 1,591 participants aged 30 years and older with confirmed COVID-19. The participants were experiencing two or more symptoms of acute infection for seven days or less. Almost half (47%) reported receiving at least two doses of a COVID-19 vaccine.
Participants were randomized into two groups: one received ivermectin, 400 μg/kg, daily for three days, while the other received a placebo.
The study found the average recovery time was 12 days in the ivermectin group and 13 days in the placebo group. Moreover, there were ten hospitalizations and deaths in the ivermectin group and nine in the placebo group.
In the CDC Health Advisory published last August, the agency reported a five-fold increase in the number of calls for human exposures to ivermectin in July 2021 compared to the period before the pandemic. According to the CDC, the effects of ivermectin overdose included gastrointestinal and neurological symptoms.
In the study by Duke University, the rate of adverse events was rare and similar in both groups (2.8% with ivermectin; 3.5% with placebo). Moreover, the ivermectin group did not experience additional serious adverse events. The researchers note, however, that the goal dose of ivermectin was limited to 35 mg, and most participants did not achieve it.
"Among outpatients with mild to moderate COVID-19, treatment with ivermectin, compared with placebo, did not significantly improve time to recovery. These findings do not support the use of ivermectin in patients with mild to moderate COVID-19," the researchers concluded.
Because of the low mortality and hospitalization rates observed in the study, the researchers say that strict conclusions cannot be made "on whether there are statistical differences in clinical event rates without much larger trials."
Moreover, the study authors note that the median time from the onset of the symptoms to receiving ivermectin was six days, which is later in the disease course than in recent antiviral trials.
It is not the first study on ivermectin for treating COVID-19, and some showed promising results. However, a 2022 analysis of 26 major trials found that more than one-third had serious errors or signs of potential fraud.
Some studies also raised questions about ethics. For example, four inmates at an Arkansas jail filed a federal lawsuit claiming that they were unknowingly given ivermectin to treat COVID-19.