Congrats for making a full working game :)
I like the idea of spreading infection, the way it is presented here may be a bit rough but it works as a proof of concept. I think I would have like it more if it was slower, like really slow, and it was more of a creepy horror action game where you can suddenly find a nest of infected people that is threatening to spread everywhere. But yeah that would be a totally different feel, here it is more like a bullet hell fast paced type of game.
The fx are simple but get the job done, which is important in a jam, same goes for the gaphics.
The music can get a bit annoying, my advice here would be: if you don't have time to craft a well written piece of music, it is better to have just a chord progession and no melody than the other way around.
On the game feel other comments have pointed you to useful resources, I just want to point out a minor issue with the camera: when you collide with something it jitters a lot, which I think is due to your code making the camera just following instantly the player position, this is pretty easy to avoid and you can find many post about that on Unity forums.