Safety of convalescent plasma therapy for COVID-19 patients and analysis of viral kinetics: A single-center, open-label, single-arm, interventional study in Japan.

Convalescent plasma therapy is an important treatment method for patients with severe coronavirus disease (COVID-19). This study was conducted to confirm the safety of this therapy. We conducted an open-label clinical trial to administer convalescent plasma transfusion in a small Japanese cohort. Blood was collected from the recovered COVID-19 patients with high anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) spike IgG titer and high neutralizing activity and stored in the National Center for Global Health and Medicine Hospital until use. Convalescent plasma was administered to COVID-19 patients who required supplemental oxygen within 3 days of hospitalization. Convalescent plasma was administered to 11 patients with moderate to severe COVID-19. One patient experienced an adverse event, such as redness of the skin around the intravenous injection site within 3 hours after transfusion. Ten patients (91%) showed clinical improvement within 28 days, and one patient died of causes unrelated to plasma therapy. The data suggest that patients with COVID-19 examined in the present study received convalescent plasma without having any significant adverse effects. We plan to conduct a randomized controlled trial to examine the clinical effectiveness of convalescent plasma transfusion in a large Japanese COVID-19 cohort.