Sex Differences Shape Viral Shedding and Symptom Patterns in Acute COVID-19, ACTIV-2/ACTG A5401 Study Finds. Lundquist Institute investigator Eric S. Daar, MD, is among the authors of a new ACTIV-2/ACTG A5401 (Advancing Clinical Therapeutics Globally) analysis examining how sex-related differences in viral shedding and symptom burden may vary by timing since symptom onset during acute COVID-19.