It does answer the question. Evolution is the result of mutations propagating through reproduction. The more copies of a virus replicating, the higher chances of mutation causing a more deleterious and/or virulent variant of the virus. As the number of viral copies and replications approaches zero, the chances of a worse strain of the virus spreading also approaches zero. Vaccines reduce viral load and spread, thus reducing the chances of mutation and spread of worse variants.
An example of this happening is the Spanish flu, which was a mutation of the common flu that was widespread and uncontrolled with vaccines at the time.
Drug-resistant bacteria are the result of misuse and incomplete use of antibiotics, and the environmental spread from waste of antibiotics. Also, bacteria can share genes horizontally, meaning resistance in one species can transfer to another quickly.
Antibiotic resistance in bacteria is mainly from misuse in humans and animals, and disease spread between the two, along with ineffective waste treatment and the leaching of antibiotics into the environment[1]. About 80% of antibiotics sold in the US are used in agriculture[2], where they are given to animals not to treat infections, but to prevent them and to stimulate growth. Over 60% of infectious diseases in humans are spread from animals, and 75% of new diseases in humans are spread from animals[3]. Shooting a few micrograms of vaccines into humans' arms is nowhere near the scale of antibiotic use or accumulation in the environment.
It's also possible to achieve herd immunity with vaccines, whereas antibiotics do not leave lasting immunity. To be effective, antibiotics must be taken when there's a bacterial infection, and their effectiveness diminishes as they leave the body.
Are these "worries" consistent? Where is the worry that polio vaccination might create worse strains of polio?
