I'd originally tacked this reply to someone's earlier message who was a doctor. But since this is basically asking for medical advice for free, that doesn't seem appropriate so just hanging it out here-
Just dealt with my elderly Mom and her husband having the flu; he had to be admitted overnight. We were told they were contagious until 24 hours after their fevers broke. After that they still might not feel well, but they'd not be infecting others. Is this not true? The local hospital has been overwhelmed with flu patients by the way, reinforcing the notion that either the vaccine didn't work very well this year (which the doctor brought up) and/or that this is a more-contagious strain than most.