Why is day 6 too late to test?

[Fluffycloudland77]

Dh had a sore throat last Thursday, yesterday he was packed with mucus in his sinuses so we got tested on what would have been day 5.

Mines negative but his is inconclusive and I’ve rebooked him for a test later but it’s day 6 now.

He’s in the shielded category so I don’t know what to do. I work in nursing homes so I don’t want to take it to them either.

I think because the virus usually last 7 days so by then, the test may come back negative even though he may have had it at the time.