COVID may be most infectious 2 or 3 days around symptom onset. 1 Sep, 2021 | 09:51h | UTC COVID may be most infectious 2 or 3 days around symptom onset – CIDRAP Original article: COVID-19 Transmission Dynamics Among Close Contacts of Index Patients With COVID-19: A Population-Based Cohort Study in Zhejiang Province, China – JAMA Internal Medicine