What is convalescent plasma (CP) and convalescent plasma therapy (CPT)?
CPT is a passive immunization method in which antibodies of an individual who has been infected and has recovered from a viral disease are transfused into a patient to increase their antibody levels. CPT can be administered via one of two methods: direct transfusion of CP and injection of concentrated polyclonal hyperimmune globulins.

Overview of the historical use of CPT
CPT has been used for many infectious diseases, as early as polio and the Spanish Flu/H1N1 in 1916 to more recent outbreaks such as SARS, MERS, Ebola, and currently COVID-19. Overall, CPT research has a long history that generally indicates safe and positive effects of CP transfusion. However, a lack of rigorous clinical trials prevents scientists from coming to a definitive conclusion on CPT effectiveness and efficacy.

Potential of CPT for the treatment of COVID-19
Due to the severity of the COVID-19 pandemic and a lack of proven treatment of SARS-CoV-2, researchers began exploring the effectiveness of CCP for COVID-19 patients very early in the pandemic. As of June 2020, there were approximately 205 registered clinical trials, 75 of which were ongoing, located in various countries across North America, Asia, and Europe. Preliminary results showed that CCP is relatively safe and possibly reduces adverse clinical outcomes (such as ventilation and hospitalization length) and mortality risks. While more recent RCTs suggest better disease progression for patients in the early stage of disease, they did not find significant benefits of CCP overall.

Policy relating to CPT use and research
Technical guidance on CPT use and research for COVID-19 was formally developed and updated by the FDA and the European Commission. These documents largely agree on issues relating to donor and recipient eligibility, procedures, storage of plasma, and record keeping. As of June 2020, WHO had yet to provide official guidance on the matter.

Ethical concerns relating to the use and research of CPT
Ethical considerations for CPT research and distribution include: 1) scientific validity; 2) principles of non-maleficence, beneficence, justice, and respect; 3) allocation for research participation or for clinical use; and 4) research in emergency situations. Additionally, prioritization of medical resources for highest risk populations and first responders may be ethical, but triage guidelines should ensure equity and maximal benefits.

CPT has been studied for a long time for various viral infections, but there is currently no consensus on its safety and effectiveness for COVID-19, due to a lack of well designed clinical trials. As of June 2020, WHO, as the international public health agency, had not issued formal guidance on CPT research for COVID-19 patients. Such guidance would facilitate consistent global research.