Most people are contagious for about 10 days. It’s not always clear how long a person is contagious because, like a lot of things with COVID-19, the exact timeline depends on many factors, said Dr. Stuart Ray, a professor of medicine and infectious diseases at the Johns Hopkins University School of Medicine in Baltimore.
https://www.huffpost.com/entry/how-long-contagious-covid-19_l_63c80929e4b01e92886088b4