After original sin, God still called man and even promised a victory. He announced that there would be a Messiah and Redeemer, a battle between the serpent and the Woman, and the final victory for her descendents: "I will put an enmity between you and the woman and between your offspring and hers, he will strike at your head while you strike at his heel" (Gen 3:15).

This passage announces Christ as the "New Adam" who superabundantly makes amends for Adam's sin. Many church Fathers see Mary as the "new Eve," the first to benefit from Christ's redemption by her Immaculate Conception and freedom from all personal sins.

Ref. CCC  410-411

Taken From The Compendium  - Catechism Of The Catholic Church