I had this huge disease scare when I was a freshman, and I looked up diseases like Ebola and that sort of thing: viruses tend to break out among younger people, stressed people, and elderly people.
Ok, so here's the thing: at best, epidemics can be prevented by using vaccines. Vaccines have limited effectiveness, because billions and trillions of viruses can break out-- all of the same kind. It's highly unlikely, because the viruses have to mutate--however the common cold is the best example. Another thing is this: People are different, so for example, that Chicken crap going on in China, (I don't know how much it was abated) there were 10 people who died and I mean 10 people out of...how many people in China? A lot.
SO, from what I gathered, you could survive for example Ebola, but you'd need to be incredibly strong--so in that sense, your immune system would have to be very top notch. You'd also of course need to have intensive care. And who knows? Maybe people are better off dying from thing such as Ebola. I believe no one has yet survived Ebola, and its a frickin horrifying, and terrible disease.
During the first outbreak of the Black Death in the 6th century, most people died, but the Emperor Justinian for example didn't...and this is interesting to note, because he was living in standards obviously much higher up than even the highest kings in western Europe. His mind was scarred permanently, but I mean hell, he survived, which is definitely interesting to note--He must have had an incredible immune system.
Cliffs: Immune system is what keeps people alive. Viruses can be fought off with anti biotics, but can go dormant, which means they basically hide themselves in your body, and only until the body is stressed, like sun burned, physical, mental stress, the thing breaks out. Like warts. Its possible the body fights it off, or it goes dormant.
Now, I don't know how updated this information is, this is info from 2 years ago.