Connors JM, Brooks MM, Sciurba FC, et al. - The ACTIV-4B Outpatient Thrombosis Prevention Trial was designed with the aim to ascertain the effect of administering anticoagulant or antiplatelet therapy on incidence of major adverse cardiopulmonary outcomes among symptomatic but clinically stable outpatients with COVID-19.

• A total of 657 symptomatic outpatients with COVID-19 were included.

• Because of an unanticipated low event rate, early termination of the trial was done.

• Participants were randomized to receive trial treatment with aspirin (81 mg once daily), apixaban (2.5 mg twice daily), apixaban (5.0 mg twice daily), or placebo.

• An adjudicated composite outcome (all-cause mortality, symptomatic venous or arterial thromboembolism, myocardial infarction, stroke, or hospitalization for cardiovascular or pulmonary cause) after 45 days was reported at the rates of 0.0%, 0.7%, 1.4%, and 0.0%, respectively, in the four groups.

• No significant differences were evident between the active groups and the placebo group.

• Overall findings yield no support for using aspirin or apixaban in the outpatient setting to lower the major adverse cardiovascular or pulmonary consequences linked with symptomatic but clinically stable SARS-CoV-2 infection.