John Gill Commentary Numbers 12:15

"And Miriam was shut up without the camp seven days: and the people journeyed not till Miriam was brought in again." — Numbers 12:15 (ASV)

And Miriam was shut out of the camp seven days
And so in later times lepers dwelt alone, and in a separate house, as long as the leprosy was upon them, see (2 Chronicles 26:21) ; Miriam no doubt was healed at once, but, as a punishment for her sin, she was obliged to keep out of the camp of Israel for such a space of time:

and the people did not journey till Miriam was brought in [again] ;
partly out of respect to her, she being a prophetess, and one that went before them, and led them with Moses and Aaron, (Micah 6:4) ; and partly for want of the cloud to direct them, which had departed at a distance from them.