Swamp thing from the saga of swamp thing by Alan Moore

Yes!

I already did

They would survive for awhile after diagnosis on a starvation diet, maybe weeks, and slipping in and out of a coma but it was a death sentence. There’s stories from the 1920’s when whole wards of kids were hit with a first dose that removed the symptoms in minutes. I can’t imagine being in that room when all that despair and anguish turned into hope and relief.

There’s a minimum speed on highways because it is dangerous to slow below that limit, the stopping distance for 70mph is around 240 feet and 2.5 sec for perception & reaction.

I’d want something that can help people and can be tested and has an immediate, dramatic effect to make it undeniable

Maybe insulin? You could literally bring comatose people back from the brink of death in minutes