SPF66 MALARIA VACCINE IS SAFE AND IMMUNOGENIC IN MALARIA NAIVE ADULTSIN THAILAND

In preparation for an efficacy trial of malaria vaccine SPf66 in Thail and, a series of overlapping Phase I trials were conducted of US-manuf actured SPf66. Here, two clinical lots were evaluated for safety and i mmunogenicity in a combined open-label trial. Eleven healthy, malaria naive, 18-44 year-old Thai men and women received three doses by subcu taneous injection in alternate arms at 0, 1 and 6 months. Safety was a ssessed by monitoring local and systemic reactogenicity and laboratory parameters. Common side effects were mild erythema, induration and te nderness at the site of injection which resolved within 24-48 h. At th ird immunization, two volunteers developed acute bilateral reactions w ith induration, erythema and pruritus limited to the sites of the seco nd and third immunizations. Eight of 11 volunteers sere-converted by E LISA, six of whom would be classified as high responders by Colombian standards. Eight of 11 volunteers developed a lymphoproliferative resp onse to the SPf66 antigen. Side effects were more common and antibody and lymphoproliferative responses greatest, among the four female volu nteers. This initial study of SPf66 malaria vaccine in Asia constitute s an essential link between the initial Phase I study in the US and su bsequent field studies in a semi-immune population in a malaria endemi c area of Thailand. This study further establishes comparability of US -manufactured SPf66 with that of Colombian provenance and substantiate s the validity of the subsequent negative efficacy results of SPf66 in a field trial in Thailand. (C) 1997 Elsevier Science B.V.