If that person is alive, then the Sacrament has all of its usual efficacy. This is not like confession, where one must be interactive with the Priest. From the Catechism:
III. HOW IS THIS SACRAMENT CELEBRATED?
1517 Like all the sacraments the Anointing of the Sick is a liturgical and communal celebration,132 whether it takes place in the family home, a hospital or church, for a single sick person or a whole group of sick persons. It is very fitting to celebrate it within the Eucharist, the memorial of the Lord's Passover. If circumstances suggest it, the celebration of the sacrament can be preceded by the sacrament of Penance and followed by the sacrament of the Eucharist. As the sacrament of Christ's Passover the Eucharist should always be the last sacrament of the earthly journey, the "viaticum" for "passing over" to eternal life.
1518 Word and sacrament form an indivisible whole. The Liturgy of the Word, preceded by an act of repentance, opens the celebration. The words of Christ, the witness of the apostles, awaken the faith of the sick person and of the community to ask the Lord for the strength of his Spirit.
1519 The celebration of the sacrament includes the following principal elements: the "priests of the Church"133 - in silence - lay hands on the sick; they pray over them in the faith of the Church134 - this is the epiclesis proper to this sacrament; they then anoint them with oil blessed, if possible, by the bishop.
These liturgical actions indicate what grace this sacrament confers upon the sick.
IV. THE EFFECTS OF THE CELEBRATION OF THIS SACRAMENT
1520 A particular gift of the Holy Spirit. The first grace of this sacrament is one of strengthening, peace and courage to overcome the difficulties that go with the condition of serious illness or the frailty of old age. This grace is a gift of the Holy Spirit, who renews trust and faith in God and strengthens against the temptations of the evil one, the temptation to discouragement and anguish in the face of death.135 This assistance from the Lord by the power of his Spirit is meant to lead the sick person to healing of the soul, but also of the body if such is God's will.136 Furthermore, "if he has committed sins, he will be forgiven."137
1521 Union with the passion of Christ. By the grace of this sacrament the sick person receives the strength and the gift of uniting himself more closely to Christ's Passion: in a certain way he is consecrated to bear fruit by configuration to the Savior's redemptive Passion. Suffering, a consequence of original sin, acquires a new meaning; it becomes a participation in the saving work of Jesus.
1522 An ecclesial grace. The sick who receive this sacrament, "by freely uniting themselves to the passion and death of Christ," "contribute to the good of the People of God."138 By celebrating this sacrament the Church, in the communion of saints, intercedes for the benefit of the sick person, and he, for his part, through the grace of this sacrament, contributes to the sanctification of the Church and to the good of all men for whom the Church suffers and offers herself through Christ to God the Father.
1523 A preparation for the final journey. If the sacrament of anointing of the sick is given to all who suffer from serious illness and infirmity, even more rightly is it given to those at the point of departing this life; so it is also called sacramentum exeuntium (the sacrament of those departing).139 The Anointing of the Sick completes our conformity to the death and Resurrection of Christ, just as Baptism began it. It completes the holy anointings that mark the whole Christian life: that of Baptism which sealed the new life in us, and that of Confirmation which strengthened us for the combat of this life. This last anointing fortifies the end of our earthly life like a solid rampart for the final struggles before entering the Father's house.
1532 The special grace of the sacrament of the Anointing of the Sick has as its effects:
- the uniting of the sick person to the passion of Christ, for his own good and that of the whole Church;
- the strengthening, peace, and courage to endure in a Christian manner the sufferings of illness or old age;
- the forgiveness of sins, if the sick person was not able to obtain it through the sacrament of Penance;
- the restoration of health, if it is conducive to the salvation of his soul;
- the preparation for passing over to eternal life.