Khoury J, et al. - In this prospective observational study, the rate of decline in the diagnostic yield of influenza PCR assay after oseltamivir administration was determined, and risk factors for prolonged shedding were assessed. Researchers here observed that negative PCR tests taken more than 48 h after initiation of treatment had low diagnostic yield. With oseltamivir treatment, prolonged shedding was observed with more severe disease, manifested by hypoxemia and lower blood pressure.