Viral shedding maximizes before or at symptom onset.
https://www.physiciansweekly.com/covid-19-viral-shedding-can...
https://www.nejm.org/doi/full/10.1056/nejme2009758
https://www.medscape.com/viewarticle/931898
https://www.nature.com/articles/s41591-020-0869-5
https://www.cebm.net/covid-19/sars-cov-2-viral-load-and-the-...