Ivermectin is ineffective in non-severe COVID-19 patients according to new study

Ivermectin is ineffective in non-severe COVID-19 patients according to new study

A recent study published in the Journal of the American Medical Association (JAMA) evaluated the effect of ivermectin on the time to recovery from coronavirus disease 2019 (COVID-19) in patients with mild to moderate disease.

Study: Effect of Ivermectin vs. Placebo on Sustained Recovery Time in Outpatients with Mild to Moderate COVID-19.  Image Credit: Carl DMaster / Shutterstock
To study: Effect of ivermectin versus placebo on time to sustained recovery in outpatients with mild to moderate COVID-19. Image Credit: Carl DMaster / Shutterstock


New antiviral drugs have been licensed for use in high-risk people in high-income countries. Even so, their efficacy in vaccinated populations is unknown, in addition to the limited global access to these drugs. Despite advances in the treatment of COVID-19, more therapies are required, especially in outpatient settings. Research on reused medicines has mainly focused on the field of hospitalized patients for the treatment of serious illnesses.

Studies of reused drugs in outpatients have been limited by design limitations, small sample sizes, and variable results. Ivermectin is an antiparasitic drug used worldwide for strongyloidiasis and onchocerciasis that emerged as a potential repurposed drug for COVID-19 in 2020. Preliminary evidence suggested a potential therapeutic effect, particularly among hospitalized patients. Dosing variability, study quality, and multiple article retractions have generated controversy.

About the study

In the current study, investigators evaluated the effect of ivermectin in early mild/moderate COVID-19 in an ongoing, double-blind, placebo-controlled, randomized trial. Recruitment for the trial began in June 2021 and is ongoing. Participants were recruited into the ivermectin group from June 23, 2021 to February 4, 2022 in the United States (USA).

Eligibility criteria were age (30 years or older), confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and two or more acute symptoms of COVID-19. Reported symptoms included fatigue, cough, fever, dyspnea, nausea, diarrhea, chills, body aches, sore throat, loss of smell/taste, nasal symptoms, and vomiting.

Exclusion criteria were hospitalization, use of study drug in the last two weeks, and contraindication/allergy to study drug. Participants were randomized using a random number generator. Ivermectin or a placebo was administered directly to the participants. They were instructed to take tablets for three days at approximately 400 μg/kg.

The primary outcome was time to sustained recovery, that is, freedom from symptoms for three consecutive days. Recovery time was the number of days from the first receipt of study drug to the third consecutive day without symptoms. Secondary outcomes were hospitalization, urgent care visits, emergency department visits, or death on day 28.

Demographic information (race/ethnicity, concomitant medications, or medical history) was self-reported by participants at screening. Participants completed daily assessments and reported adverse events through the study portal. The assessments were designed to capture data on symptoms, severity, medications, and health care visits.

Time-to-event analysis was performed using proportional hazard regression. The analysis of the main variable was a Bayesian proportional hazards model. A hazard ratio greater than one indicates a therapeutic benefit. A posterior probability of benefit > 0.95 meant that the intervention was effective.


The ivermectin group had 817 participants and the placebo cohort had 774. The mean age was 48; Participants were 59% female, 81% white, 10% Hispanic, and 7% black. In total, 47% of the participants received double vaccination. The median duration from symptom onset to study drug administration was six days.

Median time to recovery was 12 days for those in the ivermectin group and 13 days for the placebo group. The posterior probability of benefit on the primary outcome (recovery time) was 0.91 between the two study arms, less than the threshold of 0.95. The cases of hospitalization/death were lower in both groups, 10 in the ivermectin arm and nine in the placebo group.

Secondary outcomes were similar between the ivermectin (3.9%) and placebo (3.6%) groups. The investigators found no evidence of a different therapeutic effect with ivermectin for the time of symptom onset for study drug receipt, body mass index, or vaccination status compared to the placebo group. Adverse events were similar and infrequent in both arms of the study. One participant who reported not taking study drug experienced acute kidney injury.


Overall, in COVID-19 outpatients with mild or moderate illness, use of ivermectin for three days at a dose of 400 μg/kg did not show a significant improvement in time to sustained recovery compared to those receiving placebo. There was no therapeutic benefit in secondary clinical outcomes, such as hospitalization, intensive care visits, or deaths. These results do not support the use of ivermectin in COVID-19 patients with mild or moderate disease.

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