Background: Experience from influenza pandemics suggested that convalescent plasma treatment given within 4 to 5 days of symptom onset might be beneficial. However, robust treatment data are lacking.
Methods: This is a multicenter, prospective, double-blind, randomized controlled trial. Convalescent plasma from patients who recovered from the 2009 pandemic influenza A(H1N1) (A[H1N1]) infection was fractionated to hyperimmune IV immunoglobulin (H-IVIG) by CSL Biotherapies (now BioCSL). Patients with severe A(H1N1) infection on standard antiviral treatment requiring intensive care and ventilatory support were randomized to receive H-IVIG or normal IV immunoglobulin manufactured before 2009 as control. Clinical outcome and adverse effects were compared.
Results: Between 2010 and 2011, 35 patients were randomized to receive H-IVIG (17 patients) or IV immunoglobulin (18 patients). One defaulted patient was excluded from analysis. No adverse events related to treatment were reported. Baseline demographics and viral load before treatment were similar between the two groups. Serial respiratory viral load demonstrated that H-IVIG treatment was associated with significantly lower day 5 and 7 posttreatment viral load when compared with the control (P = .04 and P = .02, respectively). The initial serum cytokine level was significantly higher in the H-IVIG group but fell to a similar level 3 days after treatment. Subgroup multivariate analysis of the 22 patients who received treatment within 5 days of symptom onset demonstrated that H-IVIG treatment was the only factor that independently reduced mortality (OR, 0.14; 95% CI, 0.02-0.92; P = .04).
Conclusions: Treatment of severe A(H1N1) infection with H-IVIG within 5 days of symptom onset was associated with a lower viral load and reduced mortality.
Trial registry: ClinialTrials.gov; No.: NCT01617317; URL: www.clinicaltrials.gov.