There is no evidence that it brings any preventative or curative effects as regards covid. It has side effects, especially when taken at high dosage, which the people shilling it recommend and those taking it do. They buy the horse version as it's cheap and available without prescription. So it is indeed horse paste they are taking, even if the same substance is also used in properly dosed human products, used in specific situations where it is effective. "Anyone with a baseline knowledge of" pharmacology would also agree that the standards applied to vet and human pharmaceuticals are not the same, as well as that the active ingredient is not the only thing that matters, as e.g. how the product is packed or what other ingredients are included to ensure efficidnt uptake varies between products.
So, at best, people take a sane dose and it has no effect whatsoever as covid is not an intestinal worm. At worst, they take too much and it makes them more ill. There are indeed people hospitalised for it, whether that's a global, national, local or non-issue I can't say but that any unnecessarily sick person in the context of a pandemic takes another bed away is pretty obvious.