There is a known mechanism by which ivermectin is expected to work against covid - it inhibits the protease family of enzymes. Incedentally, Pfizer is developin

There is a known mechanism by which ivermectin is expected to work against covid - it inhibits the protease family of enzymes. Incedentally, Pfizer is developing a new (read: expensive and on patent) covid drug which also happens to work via the same mechanism. So the fact that ivermectin is an antiparasitic is irrelevant, as is the comparison to penicillin.