Answer by Tirumalai Kamala:
Vaccines can reduce risk for a specific disease but rarely completely. Why not completely?
a) Vaccines work by inducing a strong and robust immune memory. Immune memory wanes with time. This is why we are advised to get a tetanus shot every 10 years. Why does immune memory wane? We have some theories but we don’t know exactly. There is much we don’t know about immune memory.
b) Strain variation. E.g. Flu has a lot of strains. Seasonal flu vaccines target prevailing strains. They are less or not effective against strains coming down the pike next year and so on.
c) With increased regulations for vaccine safety, newer approved vaccines are cleaner, i.e. less effective in doing a. As a result, most modern vaccines require booster shots. Thus, a vaccine company can count on continuing revenue stream from vaccine booster shots.
Fallacy #2: Drugs only treat symptoms without curing the disease.
Sovaldi ()? Atrociously expensive in the US? Yes. Cure? Certainly seems to cure certain forms of chronic Hepatitis C.
As for the overarching question, it harbors an even bigger fallacy, namely, that we know everything knowable about a human disease to be able to contrive symptom alleviation alone. We know a lot about some diseases but little about many others. The latter are the ones we call of unknown etiology. That’s just a fancy way of saying we know next to nothing about them. For such, symptom alleviation is the best we can do but that’s not by choice.
Bottom line: We live in a world far from the utopia of disease prevention. We will get there when we know everything about human biology, which is rather unlikely.