This great thread reviews a study of 9 German patients looking for viral Sars-cov2 RNA & blood antibodies.

Quick summary:
•unlike SARS, high production in throat & upper respiratory tract
•lots in sputum/phlegm
•blood antibodies show in 5-14 days
•no virus in blood https://twitter.com/PeterKolchinsky/status/1246975275021348865

On infectivity & from where: live virus(cultured) found in sputum, swabs up to 8 days post infection, never in blood or stool.

So 10 day discharge of more mildly symptomatic patients ok.

The viral RNA detected at 28 days post infection in stool, phlegm is from dead virus.

Safe discharge should also be based on < 100000 viral RNA copies per ml of sputum besides 10 days.