Sorry but arguing that it's better to let people die from illness rather than fight a virus with medicine will require more than an analogy. I asked for a mech

Sorry but arguing that it's better to let people die from illness rather than fight a virus with medicine will require more than an analogy. I asked for a mechanism that would make the population more fragile overall (not only less resistant to a specific strain of a specific virus) if we train the immune system with a vaccine. Also keep in mind this is an age disease, ie those who are more likely to die from the virus will do so after their reproductive period. (Note: do you seriously believe today's teeth are more troublesome and less fit for the job than in the past ?)