The claim about the vaccines "wearing off" does not seem to be true. Compelling immunization also does not, in my view, constitute "assault," and I don't care if it makes people upset, something you could say about almost any policy imaginable.
If you haven't seen the push for boosters, seasonal shots, etc then you’re not paying attention.
As to assault, you’re right. Legally, the sovereign cannot assault (not even MBS in SA). that being said what the sovereign is doing easily falls into the common law definition of assault:
“An intentional act by one person that creates an apprehension in another of an imminent harmful or offensive contact”
Note the words “offensive”, “contact” and “apprehension”. As my lawyer friend once explained to me, merely touching someone’s arm who you know doesn't want to be touched is assault.
A vaccination necessarily requires that a needle purposely touches, pierces, and injects a foreign substance into another.
If unwanted it constitutes assault, except that the state (as the BLM folks, thankfully, explained last year) has sovereign immunity.
Either way these vaccines will not accomplish your stated goal. The vaccines wear off too quickly. The virus bifurcates too quickly. With Pfizer talking about the need for quad shots, you cant manufacture enough vaccines for the world in the various variants present.
However, forcibly injecting people (legal assault) with the vaccines will create a very angry, motivated, minority. A recipe for a society to descend to hell.