Participants and Procedures
ASYMPTOMATIC SARS-COV-2 INFECTION
Eligible participants were nonhospitalized adults 18 years or older with symptomatic SARS-CoV-2 infection documented by positive antigen or nucleic acid testing results and symptom onset within 10 days of entry; early in enrollment, eligibility was further restricted to 8 days of symptoms as more data on the kinetics of SARS-CoV-2 became available.Participants self-reported their race and ethnicity (Asian, Black, Hispanic or Latino, White, or other race or ethnicity [including American Indian or Alaska Native, multiple races or ethnicities, or other race or ethnicity]) and gender (cisgender, transgender spectrum, or not reported). These data were collected in accordance with reporting requirements for clinical trials and to ensure representation among the study participants.On day 0, participants randomized to the IM group received 600 mg of tixagevimab-cilgavimab (300 mg in 3 mL of each component, 1 component delivered to each lateral thigh [IM T-C arm]), or equivalent volumes of IM saline placebo. Participants in the IV group received 300 mg of tixagevimab-cilgavimab (150 mg of each component admixed [IV T-C arm]) or saline placebo infused over approximately 15 minutes. Visits were conducted at days 3, 7, 14, and 28 for clinical assessments and staff-collected nasopharyngeal swabs. Participants self-collected anterior nasal swabs daily through day 14 and completed a daily symptom diary through day 28.