I don't have any intimate knowledge of the process

I don't have any intimate knowledge of the process, just what I've gathered from the PRs. The way I read it, including how NP talked about it in the video, they are "safe to proceed", meaning they can start enrolling, because the first IND for mild to moderate was approved and this falls under the umbrella of that first IND. Anything they add obviously needs to be filed so it's on record, but the FDA has already said (via the approval of the mild to moderate IND) that leronlimab is safe to start studies with. It wouldn't surprise me if you're right Misiu143, and the FDA still has to give some sort of OK so there isn't a surprise trial design feature the FDA would never be OK with. But based on the wording from the video and from this PR it really does sound like this protocol is grandfathered in based on the first IND. Either way, I can't imagine the FDA would wait very long if they do have to give the OK, since it sounds like the severe trial was partly their idea. Plus, it really does sound like both of these trials could be fully enrolled within days. I'm very happy that another 300+ are about to get an extra chance to get better.