C3PO Clinical Trial of COVID-19 Convalescent Plasma of Outpatients

Registered with ClinicalTrials.gov: NCT04355767

Award Number: 1OT2HL156812-01 

Status: No new randomizations as of February 25, 2021.

NIH Press Release (March 2, 2021) 






The Clinical Trial of COVID-19 Convalescent Plasma in Outpatients (C3PO) is a multi-center randomized, single blind, two arm, placebo controlled phase III trial with blinded outcome assessment to establish the safety and efficacy of a single dose of convalescent plasma (CP) for preventing the progression from mild to severe COVID-19 illness. 

COVID-19 is a respiratory illness caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). As of May 1, 2020, over 3 million persons worldwide have been diagnosed with COVID-19 and approximately 250,000 persons have died from this disease. The majority (80%) of cases are categorized as mild, while approximately 15-20% of cases are categorized as severe, with about 5% of all cases progressing into critical illness, characterized by hypoxemic respiratory failure, shock, and end-organ failure. Among the 5% who develop severe disease, as many as 50% die. At present there is no specific therapy for preventing the progression of COVID-19 from mild to severe disease. 

Passive antibody therapy using plasma from donors who have been infected and then recovered (convalescent plasma, CP) contains neutralizing antibodies against the infectious agent.  Specifically, CP has been used in different respiratory illness epidemics, including the 1918 influenza pandemic, the 2003 SARS-CoV-1 outbreak, and the 2009 H1N1 influenza pandemic. Use of CP for emerging infections has persisted because of strong mechanistic and observational data, but efficacy has yet to be well tested or demonstrated in clinical trials.  At this moment, there is no high quality evidence to support the efficacy of CP for treating COVID-19 illness. Conceptually, CP has the highest chance of showing efficacy if used for early treatment of patients at the highest risk for severe disease and mortality.  

The overarching goal of this trial is to confirm or refute the role of passive immunization as a safe and efficacious therapy in preventing the progression from mild to severe/critical COVID-19 illness and to understand the immunologic kinetics of anti-SARS-CoV-2 antibodies after passive immunization. 

For more information on C3PO and convalescent plasma go to our In the News page.