Whoever touches a dead body, the body of a human being who dies, and does not purify himself, defiles the Mishkan of the Lord, and that person shall be cut off from Yisrael; because the water of sprinkling was not thrown upon him, he shall be unclean; his uncleanness is still upon him.
Torah Temimah: Sifrei — The verse teaches that he does not convey impurity until he dies.
English: The verse teaches that he does not convey impurity until he dies.
Limitation of the impurity to the moment of death.
A living person, even if mortally wounded, does not convey corpse impurity until the moment of actual death.