EVALUATION OF SPF66 MALARIA VACCINE DURING A 22-MONTH FOLLOW-UP FIELDTRIAL IN THE PACIFIC COAST OF COLOMBIA

A double-blind randomized placebo-controlled field trial with the SPf6 6 malaria vaccine was carried out in an endemic area consisting of 14 small villages with exclusive fluvial access, in a rain forest area al ong the Rosario River, Colombia. A total of 1257 subjects completed th e full three dose vaccination schedule on days 0, 30 and 180 (643 vacc inated group/623 placebo group) and were followed-up by passive and ac tive surveillance over a period of 22 months. One hundred and thirty-f our Plasmodium falciparum malaria episodes were detected (53 in vaccin ated group/81 in placebo group), yielding an attack rate of 5.47 cases /100 person years of follow-up (pyears) in the vaccine group and 8.44/ 100 pyears in the placebo group. The estimated vaccine protective effi cacy was 35.2% (95% CI 8.4-54.2%, P=0.01). This result supports earlie r findings that the SPf66 malaria vaccine diminishes the risk of infec tion by P. falciparum in endemic ai eas of South America. Copyright (C ) 1996 Elsevier Science Ltd.