Ok, Alice

The only response you can give to someone that has drank so much of the kool-aid they've gotten drunk on it and fallen down the Q-Anon rabbit hole. You feel the need to acknowledge their complete departure from reality but you know that providing facts from reliable sources is only going to wind them up to new levels of nuttiness so you just respond with ok, Alice and wonder if they get the reference.

Your friend: Those scary nursed in the spacesuits are trying to inject you with a vaccine designed for population control.
You: Ok, Alice.