It doesn't have to be one single base line, but there MUST be base formula, equation, etc that applies equally across all circumstances.
Ummm, no. There must not be. There's no single mathematical formula or equation, that applies to all cases of illness, but we can identify cause and effect. I can inject a pathogen into a fish at work, and place that fish into a tank with other fish, and reliably tell you, within a day or so when the sham-vaccine controls will start to die. But there isn't a mathematical formula for it. I can replicate many times and get different numbers. Eventually, we get close to the truth.
If I use a different cell culture to grow my pathogen, I can get a different answer. If I use a different disease isolate ( same virus, slightly different surface proteins), then I can get a different answer.
I find it hard to believe that you are now saying that there must be a model that applies to everything. Do you know any science history at all? The search for grand unifying theories?