The C4R observational study is collecting participant data and samples to better understand COVID-19 and the associated symptoms and side effects.

The ACTIV4B Outpatient study is testing if anticoagulation agents – blood thinners -- prevent mild infection, being treated at home, from worsening and requiring hospitalization.

The ACTIV4c Post-Discharge study is testing if anticoagulation agents – blood thinners – improve recovery from COVID-19 for individuals after being discharged from the hospital.

The ACTIV4A Inpatient study is testing if treatments that aim to prevent blood vessel injuries and blood clots improve recovery from patients hospitalized due to COVID-19.

The ACTIV3 study is testing if monoclonal antibody treatments -- laboratory-made proteins that mimic the immune system’s abilities -- improve recovery from patients hospitalized due to COVID-19.