Dose-dependent complete protection was obtained in 4 of 5 volunteers after immunization with bites from 45 P. falciparum-infected mosquitoes , in 8 of 9 volunteers with bites from 30 , and in 5 of 10 volunteers with bites from 15 ( odds ratio [ OR ] , 5.0 ; 95 % confidence interval [ CI ] , 1.5-17 ) .