Quoted from wayout440:The increasing herd immunity associated with a natural defense to a virus and the accompanying decrease in mortality has been interrupted by vaccination. This makes it difficult to predict how a vaccinated population responds to a new strain of that virus that has escaped the vaccination protection, and that population that is not immune to the new mutation it is at risk again. Natural herd immunity following exposure has been destroyed by vaccination.
Quoted from wayout440:I'm not sure what you are saying by most of that statement, but natural immunity by definition:
Naturally acquired active immunity occurs when a person is exposed to a live pathogen, and develops a primary immune response, which leads to immunological memory. This type of immunity is "natural" because it is not induced by deliberate exposure.
It applies to both viral and bacterial pathogens.
I don't quite understand the point you're trying to make.
Are you saying people shouldn't be vaccinated against diseases and let nature take its course? If that was the case, we would still be dealing with smallpox, measles, mumps, rubella, polio, diphtheria, whooping cough, tetanus, hepatitis B, tuberculosis, plus a few others that were quite widespread and very deadly in many cases the early-mid 1900's.
Vaccines have pretty much eliminated those diseases. They haven't started coming back until recently when people have started opting out of taking the vaccines that prevented people from being susceptible to them.
For people who don't have a fully working immune system (or one at all--either temporarily or on a permanent basis, or can't take the vaccine because of other medical complications/conditions)--they can't fight off these diseases on their own, and rely on "herd immunity"--which means that everyone around them who is capable of being vaccinated is, and therefore can't be carriers for it or potentially pass it along to that immuno-compromised individual. If they do catch a disease like one of the ones listed above, it can basically be a death sentence for them.
Flu vaccines are in a slightly different category since there is some educated guesswork that needs to happen in order to figure out what strain of the flu virus might be making the rounds, so effectiveness may vary from year to year. The influenza virus has so many strains and mutates so much that there is no "one-and-done" vaccine like with other diseases.