Isn't Ivermectin most effective at the onset of symptoms [0] ? From the article "They looked at data from all patients; then analyzed data from patients who received ivermectin or a placebo 24 hours before they were hospitalized" This sounds like Ivermectin was given when symptoms where so severe, hospitalization was required. This could well be too late for Ivermectin to be effective.
[0] https://www.ijidonline.com/article/S1201-9712(20)32506-6/ful...