the more important thing is that it has been around so long that we know the side effects and the rates they occur. The NEGATIVES are pretty well established even if the positives for this virus are not. Therefor we know how safe, or unsafe, using this drug is so continued studies will only tell us if it actually does what we hope it does in relation to this illness. No further study is really going to provide us with any more negatives, they're well known.