human sized doses of Ivermectin have used for quite a while to treat them.
If a patient presents Covid and also has parasites, it makes sense to treat the parasites as they are a huge burden on the body. Once the parasites are gone, that is one less co-morbidity on the random variable menu and the patients have a much better chance of recovery from Covid.
This is my theory of why Ivermectin became a topic of conversation for Covid treatment.