On Sept. 10, 2020, the National Institutes of Health launched two of three adaptive Phase 3 clinical trials evaluating the safety and effectiveness of varying types of blood thinners to treat adults diagnosed with COVID-19. Part of the Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) initiative, these trials will be conducted at more than 100 sites around the world and will involve patients in various clinical settings ﾗ those who have not been hospitalized, those currently hospitalized and those discharged after hospitalization for moderate to severe disease.

Collectively known as ACTIV-4 Antithrombotics, the trials will provide critical insights that could help guide the care of patients with COVID-19, particularly those who suffer from life-threatening blood clots. The trial for hospitalized COVID-19 patients and the trial for patients with COVID-19 who have not been hospitalized are now underway. A third trial to start later will focus on patients discharged after hospitalization for moderate to severe COVID-19 disease. All three clinical trials will be coordinated and overseen by the National Heart, Lung, and Blood Institute (NHLBI), part of NIH, and funded through Operation Warp Speed.

Researchers have noted that many patients who have died from COVID-19 — the deadly disease caused by SARS-CoV-2 — had formed blood clots throughout their bodies, including in their smallest blood vessels. This unusual clotting, one of many life-threatening effects of the disease, has caused multiple health complications, from organ damage to heart attack, stroke and pulmonary embolism.

ACTIV-4 Antithrombotics will be recruiting at sites with significant COVID-19 burden and are interested in enrolling patients in studies testing potential treatments to prevent or reduce the formation of blood clots. The adaptive design of the protocol allows different blood thinners to be started, stopped or combined during the study in response to emerging trial data. This approach accelerates the timeline for testing different agents without compromising safety.

Antithrombotics, also known as blood thinners or anticoagulants, keep blood protein and platelets from turning into clumps or sticking to each other, but doctors have not yet figured out if, and at what point during the course of the disease, blood thinners might be effective at treating patients with COVID-19.