The effectiveness of ivermectin is determined by dose.
Let's use the anti-malaria drug Malarone as an example. For prevention purpose, the dose is one pill per day. But if the patient contracts the virus, the treatment requires a much higher dose. Dose matters.
Similarily, the prevention, early treatment, and late treatment of COVID using ivermectin require different doses, ranging from 0.2mg/KG to 0.6mg/KG. Such protocol was made based on clinical experience by frontline doctors at FLCCC.net.
There are already several ivermectin trials published on the CDC/FDA websites. However, all those trials used much lower doses than the FLCCC protocol. Therefore, the results were not satisfying. CDC/FDA use it as an excuse to prevent the use of ivermectin for COVID.
So, it's not about whether there is a trial, but about whether the trial makes sense by using effective doses.