[NANP](19)-5.1 - A MALARIA VACCINE FIELD TRIAL IN NIGERIAN CHILDREN

[NANP](19)-5.1 is a recombinant Plasmodium falciparum vaccine consisti ng of 19 repeats of the sporozoite surface protein [NANP] and the schi zont export antigen 5.1. In a previous study, an experimentally infect ed subject (with a history of malaria exposure and an elevated pre-imm unization lymphocyte stimulation index to antigen 5.1) showed parasita emia but no signs of clinical malaria, In an attempt to find a compara ble partially immune population, we tested the vaccine in 194 schoolch ildren (6 to 12 years, vaccine and placebo groups of equal size), who already possessed a certain degree of immunity It was hoped that this immunity would be boosted by the vaccine. During the 12 weeks of obser vation, no child developed clinical malaria. Analysis of serum taken b efore and after immunization revealed that, except for eight children, all had considerable levels of antibodies to both antigens. We conclu de that the trial should be repeated in younger children who are still vulnerable to clinical malaria.