I agree with you that a vaccine creates many problems. And that the potential for abuse is high.
But I also think, as other person stated, there are legitimate situations where people would choose it for themselves.
I don’t know what the answer is, but I do think it would be strange to withhold a treatment from willing individuals just because others would abuse it.with that logic, it would be bad to ever create anything beneficial that could also be weaponized.
I say I would be in favor of a vaccine being created if there were strict regulations that were put in place and all superheroes (avengers etc) were involved in holding the use of said vaccine accountable for its intended purpose. (Edited to add: I agree it would be best that this not be developed or distributed By a government).
Btw on a side note, funny that a similar story is currently unfolding in “the gifted”.