Ivermectin has been touted as the wonder drug solution to the Covid-19 crisis. Several trials have suggested it may have some benefit. But the largest trial yet comparing ivermectin to placebo was published on Friday. It found no statistically significant benefit from ivermectin but possible harm from the drug.
Yet even this trial is too small to definitively settle questions about ivermectin’s safety and efficacy. Nevertheless, even if some future trial does find benefit, there is now little doubt that this is not a wonder drug; whatever benefits it may have are at most modest.
This latest trial was conducted in Argentina by Julio Vallejos and colleagues. The results were published in BMC Infectious Diseases on 2 July. It’s main outcome was to see if ivermectin reduced hospitalisation in people with Covid-19.
The trial included 501 volunteers, 250 randomly assigned to take ivermectin and the remaining 251 were assigned to a placebo arm. The trial used quite a complicated dosing regimen that depended on patient weight.
Incredibly it was extremely hard to find patients for the trial. Why? Too many Argentinians it seems were already taking ivermectin. Of 15,968 people who tested positive for Covid and were excluded from taking part in the trial, 12,356 could not participate because they were already taking ivermectin. (We are also hearing anecdotal reports of South Africans using ivermectin.)
Fourteen people on the ivermectin arm were hospitalised versus 21 on the placebo arm. Besides this not being a statistically significant difference, there were more people with diabetes, perhaps the most serious risk factor for serious Covid, in the placebo arm; there were also more people with hypertension in the placebo arm (weight and age were well matched between the arms). Quite clearly ivermectin was not shown to be beneficial in this trial.