Can Vampires get ill?
Like can they get a cold/flu or can they get cancer?
Does anyone know?

I can't speak for everyone but I can't.

I don't have a clue about anything like cancer or severe disease, but I would think that a vampire could become ill due to a virus at the right timing. The only times I ever do catch a cold are when I am pretty much 'starving' myself, and for a long time. Though, that could just be my body having such a hard time with the starvation that my fatigue feels worse and I begin to have 'symptoms' as with a real cold. I really don't know.
I don't believe the immortals can get sick. The idea of them getting sick doesn't sound right. If they are immortal, then they have a completely different... defense?... than anyone else.

you mean the common Sang and Psi? Or are you speaking of Immortal?
I know Sang and Psi can get sick. I guess you would have to ask an Immortal to know the rest.

It is hard to say

I'm Sang. And I haven't been sick, not even a cold, since I Awakened. That was nine years ago. I think that Sang's and Psy's have the exact same attributes of a quote "Immortal." We are the same. Nothing in this world lasts forever. But we do live longer. That's been proven. I can't speak for other vamps but I think it's really hard for a vamp to get sick. But it also depends on each person's body.

Ugh. I wish mortals couldn't get sick. I feel terrrible at the moment. -stupid virus-

&I wouldn't expect they could. It would just be.. odd. But maybe, I don't know. I do know sharks can't get ill. Maybe sharks and immortals have a similar immune system. :/

From my own experience yes we (HLVs) can get sick. I suppose if one keeps their energy levels topped up then it is harder to catch a virus but if one is run down or not feeding properly then we can catch viruses and such.

when i was younger i use to get sick, but now i never get sick

For my self it does take a good bite for me to get sick. I don't get the common cold or flu. It's what the body goes threw when you've done too much for too long. As mortals we do need some sleep. We do need to regenrate. I can be pushed past the point of breaking. Yet, I can't die from it though. A good day of rest and some well blood. I right back on my feet the next day.