Convalescent Plasma-Mediated Resolution of Covid-19 in Humoral Immunodeficiency

Convalescent plasma (CP) is widely used to treat Covid-19, but without formal evidence of efficacy. Here, we report the beneficial effects of CP in a severely ill Covid-19 patient with prolonged pneumonia and advanced chronic lymphocytic leukemia (CLL), who was unable to generate an antiviral antibody response of her own. On day-33 after becoming symptomatic, the patient received CP containing high-titer (ID 50 >5,000) neutralizing antibodies (NAbs), defervesced and improved clinically within 48 hours, and was discharged on day-37. Hence, when present in sufficient quantities, NAbs to SARS-CoV-2 have curative potential even if administered relatively late in the disease course.