Convalescent Plasma for COVID-19: More Questions Than Answers

Convalescent plasma has been suggested as a possible treatment option for COVID-19. Now, investigators from China have conducted a multicenter, open-label, randomized clinical trial of convalescent plasma added to standard of care among patients with confirmed SARS-CoV-2 infection, stratified into severe or life-threatening disease. Convalescent plasma was obtained from persons who had recovered from COVID-19 and were more than 2 weeks out from hospital discharge. Only plasma with an IgG titer against the S protein-receptor binding domain of at least 1:640 was used, at a dose of 4 to 13 mL/kg (median infusion, 200 mL). The primary endpoint was time to clinical improvement within 28 days, defined as discharge or a reduction of 2 points on a 6-point disease severity scale.

Although a 200-participant study was planned, early termination for lack of patients in Wuhan after March 27 occurred, with 103 participants enrolled, 52 (23 with severe and 29 with life-threatening disease) in the convalescent-plasma group and 51 (22 with severe and 29 with life-threatening disease) in the control group. Median age was 70 years; 58.3% male. Clinical improvement occurred in 27 convalescent-plasma recipients (51.9%) and 22 control patients (43.1%), a nonsignificant difference. Among those with severe disease, the primary outcome occurred in 91.3% versus 68.2%, suggesting a possible benefit, but the test for interaction by disease severity was not significant. Convalescent plasma treatment was associated with higher rates of negative SARS-CoV-2 polymerase chain reaction tests from nasopharyngeal swabs, suggesting antiviral activity. The early termination could have underpowered the study, the authors note.