The risk of SARS-CoV-2 spread among COVID-19 patients to their close contacts was strongest in the 2 days before and 3 days after symptom onset and when index patients were mildly or moderately ill rather than asymptomatic, according to a US study of Chinese patients today in JAMA Internal Medicine.The researchers wrote. "Infected contacts of asymptomatic index patients were less likely to present with COVID-19 symptoms, suggesting that quantity of exposure may be associated with clinical presentation in close contacts."Most secondary cases were mild, moderateResearchers from the University of Georgia at Athens led the study, which included 730 COVID-19 index patients diagnosed as having COVID-19 from Jan 8 to Jul 30, 2020, and 8,852 close