The alternative is a about a 40% chance of survival without the drug. With the drug, maybe it will be higher, but maybe it will be lower. We don't actually know

The alternative is a about a 40% chance of survival without the drug. With the drug, maybe it will be higher, but maybe it will be lower. We don't actually know (though this new trial is very encouraging). A bad drug could also cause suffering beyond what Ebola causes: even if the patient was going to die anyway, it could make their death even more painful.