Figure 5. Vaccine efficacy against all episodes of clinical malaria (primary case definition) during an 18-mo follow-up period after dose 3 in children 5–17 mo of age at enrollment, ordered by increasing malaria incidence at each study site (intention-to-treat population).

Interaction p-value = 0.8100. The size of each blue square reflects the relative number of participants enrolled at each study site; the horizontal bars show the lower limit (LL) and upper limit (UL) of the 95% confidence interval. Study sites are ordered from lowest (Kilifi) to highest (Siaya) incidence of clinical malaria, defined as a measured or reported fever within previous 24 h and parasite density >0 parasites/mm³ (i.e., clinical malaria secondary case definition), measured in control infants 6–12 wk of age at enrollment during 12 mo of follow-up. VE is VE against all episodes of clinical malaria meeting the primary case definition, unadjusted for covariates. Clinical malaria primary case definition: illness in a child brought to a study facility with a temperature of ≥37.5°C and P. falciparum asexual parasitemia at a density of >5,000 parasites/mm³ or a case of malaria meeting the primary case definition of severe malaria.