The vaccines that have been administered twice now may not have much meaning.
ご質問ありがとうございます。
"The vaccines that have been administered twice now"=「今、2回施したワクチンは」
"may not have much meaning."=「あまり意味がないかもしれない。」
☆"meaning"の代わりに"effect"=「効果」も使えます:"may not have much effect"(あまり効果が無いかもしれない)
ご参考に。