I got the Moderna, and my left arm was useless for roughly 38 hours. When they say "your arm will probably be sore" they aren't talking about normal injection soreness. You won't even feel the needle, in fact. You'll feel a cloud of ghostly bees land on you in a half hour -- and then (roughly four hours later) you'll feel your arm's muscles ascend to a higher plane of existence and God start punching you in the shoulder if you move anything above the elbow.
That said, I had lots of energy and was thinking only mildly foggy. That's both upside and downside, though -- I kept on forgetting I only had one arm to use while the other was tucked up against me like a T-rex nubbin, trying to reach for things, and falling over in a wave of pain. Also dropping my laptop from a height of roughly 1.5 to 2 inches, constantly, as muscle memory betrays me.
As these things go, it's the worst vaccine I've ever had and better than literally any illness I can remember having.
