The vitality/life.force/spirit level is , in the sense of "strata" just below the immune system .
When this level is healthy then the immune system is strong and will repel any invaders .
However there will always be hereditary imperfections that allow external micro- organisms a foothold .
Normally if caught in time and treated homeopatically no serious harm will occur.
No , our immune systems have pockets into which microoganisms can fit . This is what is meant by 'latency'.
This of course has a relationship to AIDS .