They advised her correctly. My brother got a test on the day he started a fever. Over the next couple of days he lost taste, had massive headache, cough developed, congestion, nausea, O2 leveles declined, etc. Doctor told him his test would certainly come back positive. Four days later he was in worsening condition and got his test result back. It was negative. His doctor told him it was certainly a false negative and to get tested again. He did. In the meantime by day 7 he now had all of the symptoms and his oxygen dropped below 92%, the number the doctor told him to go to the ER with. He couldnt keep anything down and was confused. He went by ambulance and when he got there was basically in a fight for his life. Kidney failure, liver enzymes 7 times high normal, DDimer numbers through the roof, indicating clotting, advanced ARDS in both lungs with O2 now in 80s, etc. They did a COVID test, which they had to wait to get results back, and started him on COVID protocols. The next day after being admitted to the hospital, day 8, he got his second test result back from day 4 as positive. The hospital test also came back positive the next day.
Bottom line is your employee doesn't need to be in the office with symptoms. My brother got it from someone who came to work with symptoms and wouldnt wear a mask. She only tested after her mother inlaw came back positive, a week later. She got a positive test result the day my brother started a fever. False negatives are prevalent. If she tests negative again and is symptom free and has no fever for a couple of days, she could return, but dont risk it on a single test.
My brother was 42, healthy as a horse, didnt take a single medication. Almost 2 months after being discharged he has scarring in both lungs and still has a cough and gets winded very easily. We are hoping for evidence of scarring in lungs going away on next scan in 3 months.