Ambrose of Milan

Now in a mystery the people pollute the Church, that another people might succeed, gathered together from foreigners, leprous indeed at first before it is baptized in the mystical stream, but which after the sacrament of baptism, washed from the stains of body and soul, begins to be a virgin without spot or wrinkle.

Catena Aurea by Aquinas ↗

Bede

And there were many lepers in Israel under Elisha the prophet, and none of them were cleansed, except Naaman the Syrian. Because the story is well-known, it is necessary to disclose a few things about the mystery. And thus Naaman the Syrian, who is interpreted as "beauty," represents the people of the nations, once stained by the leprosy of unbelief and sins, but purified from all foulness of mind and body through the sacrament of baptism. …

On the Gospel of Luke ↗

Bonaventure

Another example for the confirmation of the aforesaid concerning Elisha is introduced, when he says: And many lepers were in Israel under Elisha the prophet: whence in 4 Kings 7 it is said that in the time of Elisha "four leprous men were near the gate of Samaria," and many others in similar necessity. …

Commentary on Luke, Chapter 4 ↗