rickair7777

They usually are, odds of a random mutation getting around a vaccine at this point are slim, that would require a lot of random genetic luck since there's no evolutionary pressure to drive that now. Once vaccines are deployed on a large scale, then odds increase slightly that it might mutate around the vaccine.

Mutations are quite random, a mutation which provides a specific benefit in the face of evolutionary pressure does not necessarily retain all of the bug's original features, or result in an overall "improved" version. It might, and often does, result in a tradeoff. Very rough analogy: take a B-52, cost-effective and carries tons of bombs with a long range... but if the enemy deploys sophisticated air defense systems you might need stealth, supersonic cruise at low altitude, and counter-measures. By the time you make those adaptions, you probably had to sacrifice a whole lot of payload.

Also with covid, natural selection favors spreading. It does not favor severe illness. So it could drift away to become milder over time. In fact severe illness is probably an evolutionary dead-end with humans because that causes people to do things to mitigate spread (unlike animals). There are coronaviruses which are part of the spectrum of bugs which cause the common cold... those we just tolerate because they're a minor nuisance, not a real health risk.

But even mutation around a vaccine's probably not a catastrophe, vaccine might still provide partial protection, bug might become less contagious or less dangerous, etc. Plus we can tweak the vaccines, especially the mRNA ones. Worst case, probably ends up like the flu shot, with period adjustments to an annual vaccine.