Leviticus 15:28

But if she be cleansed of her issue, then she shall number to herself seven days, and after that she shall be clean.

After her issue has stopped, the woman must number seven days to herself for cleansing, and only after that is she counted clean. The seven days are counted after she is cleansed of the issue, making full completion of the period the condition of cleanness.
The verse belongs to the purification laws regulating uncleanness and bodily issues, grouped with the laws about uncleanness and leprosy. Its rule for cleansing after the issue ends stands within those purification laws in which she became clean on the eighth day.

It is included among the regulations in Leviticus 1-16 that formed part of the yearly service of the Levitical sanctuary, which typified Christ's ministry in the heavenly sanctuary. The visible, physical purification it requires had to take place before the sanctuary's cleansing by blood, thus preparing what had become physically unclean for its real cleansing. The uncleanness and leprosy treated in this setting are a fitting type of sin.

The verse shows the exceeding sinfulness of sin and stands as one of God's mighty object-lessons in Leviticus. The sacrifices and slain beasts connected with these laws are types of Jesus Christ pointing forward to the Lamb of God that takes away the sin of the world, and the verse gives blessing only when He is seen in it. Her becoming clean on the eighth day is a type of the new creation.

Applied to recovery from infectious disease, the verse requires the patient to remain apart during the seven-day cleansing period and then to wash clothes and bathe in running water, which helps prevent the infection from spreading or returning. As part of the cleansing truths given to ancient Israel that should not be abandoned, the verse is a lesson for God's people and is applied to health reform as preparation for the Spirit to dwell in clean vessels and for the latter rain.