Viruses (or bacteria) don't "evolve to bypass" vaccines, antibiotics, or anything else. They generally have a pretty constant mutation rate, the vast majority of which are deleterious.
The more people that have a virus, the more copies are out there mutating, and the more mutations (in total) you'll see.
If you introduce negative pressure, like a vaccine or antibiotics, some of those mutations that were previously deleterious will turn out to be a net benefit. E.g: A thicker cell wall in bacteria makes it harder to absorb nutrients, but also increases the dose of antibiotic it can survive. These mutations happen all the time by chance, but in the absence of the vaccine/antibiotics, they are less fit and will tend to die off.
A vaccine that eliminates a virus is likely to result in less infections. Less infections means less mutations means less chance for a dangerous variant. If some variants do evolve that escape the vaccine, odds are good that they will be less dangerous than the original, not more.
This notion appears to go against all the expert advice against (ab)using anti-biotics. Sure, less infections means less chance for mutations, but due to the fundamental forces at play, the resistant mutations will spread faster through the resistant population and eventually become the prevalent strain.
Unless you can eradicate the virus or bacteria completely (mass effective vacination), the tools we create to fight them are really only delaying the inevitable.
>If some variants do evolve that escape the vaccine, odds are good that they will be less dangerous than the original, not more.
From my understanding, this is not the case. It's pure chance whether a mutation is advantageous or disadvantageous. If you are looking on a per-mutation basis, then sure, it's likely the mutation is disadvantageous. But at a population level, it's likely that atleast one advantageous mutation will emerge reasonably quickly when we are talking about something at the scale of several thousands of infections.
Seeing as we've wiped out multiple viruses completely, but have yet to eliminate any bacterial diseases, I believe there is an important difference between vaccines and antibiotics.
Perhaps viruses are simply more specialized, so it's easier to eliminate anywhere to hide by innocculating affected populations, while bacteria are more general purpose and can survive even without living hosts.
Yes, I thought we eradicated Polio, too. I see I was wrong. But apparently we are very close to eliminating a disease caused by a nematode parasite, too [1]. Fascinating.
Antibiotic-resistant bacteria are bad not because they're more dangerous than regular bacteria, but because they are harder to treat with those antibiotics.
As for your second point - mutations are happening whether or not we vaccinate. Vaccination does not cause mutation.
The more people that have a virus, the more copies are out there mutating, and the more mutations (in total) you'll see.
If you introduce negative pressure, like a vaccine or antibiotics, some of those mutations that were previously deleterious will turn out to be a net benefit. E.g: A thicker cell wall in bacteria makes it harder to absorb nutrients, but also increases the dose of antibiotic it can survive. These mutations happen all the time by chance, but in the absence of the vaccine/antibiotics, they are less fit and will tend to die off.
A vaccine that eliminates a virus is likely to result in less infections. Less infections means less mutations means less chance for a dangerous variant. If some variants do evolve that escape the vaccine, odds are good that they will be less dangerous than the original, not more.