Convalescent Plasma

Convalescent plasma (CP) is a passive polyclonal antibody therapy that has been successfully deployed during epidemics and pandemics. CP's putative mechanism of action is attributed to antibodies with direct neutralizing as well as other nonneutralizing activity. It is generally well tolerated and rarely associated with serious adverse effects. COVID-19 convalescent plasma (CCP) was one of the most common treatments deployed early in the pandemic. Rapid deployment was feasible as a combined patient/donor, hospital and blood center initiative. The Expanded Access Program (EAP) provided a model for widespread access and allowed the evaluation of key safety metrics following transfusion of CCP. Currently available randomized trial data suggest that CCP is most effective when transfused with high neutralizing titers to infected patients early after symptom onset when the viral load is relatively low. The trial data also strongly support the clinical futility of CCP after patients have developed high antibody titers or the disease has entered the aviremic phase. The Association for the Advancement of Blood and Biotherapies (AABB) clinical practice guidelines recommend against CCP use for post exposure prophylaxis and suggests CCP transfusion in addition to the usual standard of care in the outpatient setting for COVID-19 patients at high-risk of disease progression. In the inpatient setting, AABB recommends CCP transfusion (in addition to the usual standard of care) to be restricted to patients with preexisting immunosuppression or those who do not have SARS-CoV-2 antibodies detected at admission.