Obviously, vaccines have been effective against some viruses.
But this success led to a faith in the medical field that has been exploited. Some viruses are debated as to whether or not they exist in the first place, and then you compound that with the ambiguity of human studies….
The flu vaccine, for example, is one I do not believe works. Getting the government out of our pockets and our economy back on track so we don't have to be at death's door before calling in at work would do more to stop the flu than any vaccine as we understand the concept, at least.
Obviously, mumps, rubella, etc are where the vaccines are demonstrated more effectivem. Though it can be argued that they are no longer necessary as mandatory… Yet a city full of unvaccinated people is food for explosive viruses like mumps.
There again… Civilization survived in the face of constant plagues, before. Perhaps we are trying to ascribe a role beyond our wisdom when we require vaccines of our population.