Nature and our human ancestors have evolved and refined the immune system from the beginning of human existence to the present. Injections into the human body (i.e. vaccines) have never been a natural occurrence among humans historically and throughout evolution. Relative to how long humans have been in existence, vaccines are a very new practice (a mass experiment with unknown effects like russian roulette).
The concoction of whatever filth/germs is inside a vaccine will produce antibodies to "something" which does not and will not ever exist in nature, with the advertisement that those antibodies will protect you from actual nature-occuring germs in the future. Your vaccine-influenced newly altered immune system is in no way an "improvement" for your natural health & your innate, naturally balanced immune system.
When a human is naturally exposed to germs that occur in nature, that human may NEVER develop the disease that supposedly that germ "causes". So the germ really doesn't "cause" disease, if that person never develops the disease after germ exposure.
Since the beginning of human existence, it has been a regular occurrence where everyone in a social setting is exposed to said "deadly plague" germs, but some people will develop disease and some people will never develop the disease. The PR industry uses the Germ Theory to promote vaccines & they love to $ignore$ this fact. Just because a germ is present, it does not automatically mean that it will be the causative agent for disease.
But, the PR industry and any other supposedly "independent third-party" endorser who pretends to have $no conflict of interest$ (i.e. FDA, CDC & any other applicable foundation or organization; just insert the name here)...they will sure do everything in their power to get you to believe that germs are the causative agents, as long as commercial value remains (i.e. vaccines).