A field trial to assess a blood-stage malaria vaccine

January 01, 0001

A field trial to assess a blood-stage malaria vaccine

Blood-stage malaria vaccines are intended to prevent clinical disease. The malaria vaccine FMP2.1/AS02A is a recombinant protein based on apical membrane antigen 1 (AMA1) from the 3D7 strain of Plasmodium falciparum. These Mali and US investigators conducted a double-blind, randomized trial, in which they immunized 400 Malian children with either the malaria vaccine or a control (rabies) vaccine and followed them for 6 months. The primary end point was clinical malaria, defined as fever and at least 2500 parasites per cubic millimeter of blood. A secondary end point was clinical malaria caused by parasites with the AMA1 DNA sequence found in the vaccine strain.

They found: "The cumulative incidence of the primary end point was 48.4% in the malaria-vaccine group and 54.4% in the control group; efficacy against the primary end point was 17.4% (hazard ratio for the primary end point, 0.83; NS). Efficacy against the first and subsequent episodes of clinical malaria, as defined on the basis of various parasite-density thresholds, was approximately 20%. Efficacy against clinical malaria caused by parasites with AMA1 corresponding to that of the vaccine strain was 64.3% (hazard ratio, 0.36). Local reactions and fever after vaccination were more frequent with the malaria vaccine."

The authors concluded: "On the basis of the primary end point, the malaria vaccine did not provide significant protection against clinical malaria, but on the basis of secondary results, it may have strain-specific efficacy. If this finding is confirmed, AMA1 might be useful in a multicomponent malaria vaccine."

This is a start in much needed malaria vaccine development.

For the full abstract, click here.

N Engl J Med 365:1004-1013, 15 September 2011 © 2011 to the Massachusetts Medical Society
A Field Trial to Assess a Blood-Stage Malaria Vaccine. Mahamadou A. Thera, Ogobara K. Doumbo, Drissa Coulibaly, et al. Correspondence to Dr. Plowe: [email protected]

Category: B. Blood/Immune Mechanisms. Keywords: malaria, vaccine, apical membrane antigen 1, recombinant protein, Mali, randomized controlled trial, journal watch.
Synopsis edited by Dr Linda French, Toledo, Ohio. Posted on Global Family Doctor 27 September 2011

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