Cheng P.K., Wong D.A., Tong L.K., et al. (2004). Viral Shedding Patterns of Coronavirus in Patients with Probable Severe Acute Respiratory Syndrome. (Abstract only.) Lancet. 363 (9422):1699-700.
The authors studied viral shedding of SARS coronavirus to improve diagnosis and infection control. They found that overall, peak viral loads were reached at 12-14 days of illness when patients were probably in hospital care, which would explain why hospital workers were prone to infection. Low rate of viral shedding in the first few days of illness meant that early isolation measures would probably be effective.