Free as in it's not a subscription service to get a booster shot. Whether or not you use taxation as a loophole to support the argument is beside the point. The implication of OP's post is that after the free first two doses they'll start charging for boosters, which is incorrect.
Free as in the vax companies are not charging, or free as in the government will continue to pay our tax dollars to Big Pharma?
Free as in it's not a subscription service to get a booster shot. Whether or not you use taxation as a loophole to support the argument is beside the point. The implication of OP's post is that after the free first two doses they'll start charging for boosters, which is incorrect.