Short answer: YES :-( Long answer: From my understanding, mold spores have a half life of 10+ year. So they live long. However, if the source of the moisture has been eliminated, then one can simply hepa vacuum and wipe the surface. However, walls are porous and cannot be wiped. So even if the wall is dry, the infested portion needs to be taken out. While taking out, spores will fly all over. So we need to contain the space. Most of the time, air will still flow from the contained space to the rest of the house. So run a negative air machine that takes the air from the contained space to outside the home.
