flu interactivity is already amazing and contagious , which it always been. but there's some issues with it. i'll post some of my opinions of suggestions towards this illness.
1: sneezing and coughing should drain a lot of stamina also interrupt whatever you're doing. and they should be at least a minute apart.
2: Melee damage should be half the damage from flu infected person.
3: body heat over 41 Celsius if not treated should lead to unconscious state, then death.
4: if you pass flu or any disease u should be immune to it.
5: coughing lightly should be the last stages of the disease.
anyone may elaborate on this subject you're more than welcome.