The verses here in Leviticus 15 are not directly discussed in the NT but they are alluded to. Many of us remember the story of the woman who had been bleeding for 12 years. It’s a beautiful story of persistence as she knows that if she just gets a touch of Jesus’ robe, she will be healed. Per the law, she should have been cut off from society and labeled unclean. Jesus allowed her to touch Him. And knowing what we do about these laws in Leviticus 15, it makes sense as to why she was so afraid when Jesus addressed her.
Immediately Jesus, perceiving in Himself that the power proceeding from Him had gone forth, turned around in the crowd and said, “Who touched My garments?”
Mark 5:30 NASB
And He looked around to see the woman who had done this. 33 But the woman fearing and trembling, aware of what had happened to her, came and fell down before Him and told Him the whole truth. 34 And He said to her, “Daughter, your faith has made you well; go in peace and be healed of your affliction.”
Mark 5:32-34 NASB
Again, the moral of the story is that now Jesus had come to draw men and women as sinners to Himself. There was no amount of “unclean” that could stop Him from interacting with His children.
It’s also very possible that these OT rules regarding uncleanliness were instructed to discourage abnormal sexual behavior and to encourage self-control within marriage. In this context, the purpose of these laws runs parallel with many passages in the NT. It is interesting to consider that under the law, excommunication was a primary method of upholding the standard of morality. In the NT, we rely on exhortation of the Word in order to empower us through God’s Spirit to obey in righteousness.