There’s a glitch that sometimes occurs in Virus where your model doesn’t change to a zombie after getting infected, so you’re just wildly running and swinging as a crazed anime girl or rabid Pokemon. It’s genuinely hilarious and horrifying.
I was somewhat disappointed to find that the Infection milestone reward for 1,000,000 XP only replicates half of this experience, giving you the ability to swing and roar, but leaves the movement/idle animations alone.
It would make getting that 1 million XP more worth it if this were added.