Parasitemia was detected through daily blood films starting 7 days post challenge; volunteers were censored at 30 days post challenge if no parasitemia was detected. Volunteers who developed parasitemia were treated with a standard oral course of chloroquine (total 1500 mg base given in divided doses: 600 mg initially followed by 300 mg at 6, 24 and 48 h) under

direct supervision. For the Phase 1 trial all analyses are presented for the intention to treat (ITT) population which included all subjects who received at least 1 dose of study vaccine. For the Phase 2 trial, safety data are presented for the ITT population and immunogenicity and efficacy data for a modified ITT population, excluding volunteers receiving vaccine subject to temperature deviations (see Section 3.1). Summaries were calculated for the incidence, intensity, and relationship of solicited and unsolicited Bcr-Abl inhibitor AEs (see Supplementary Appendix). The percentage of subjects with seropositive levels of anti-CS antibodies (≥1 μg/mL) was determined. Antibody titers were summarized by GMT with 95% CI. GMT calculations were performed by taking the anti-log of the mean of the log titer transformations. Anti-CS antibody titers of <1 μg/mL were

assigned a value of 0.5 μg/mL for the purpose of GMT calculation. For each vaccine group, anti-TRAP antibody titers were described and GMTs with 95% CI were calculated; no 0 values were found. Descriptive analyses in terms Protein Tyrosine Kinase inhibitor of LP response, expressed as stimulation indices (SI*), and measurements of IFN-γ and IL-5 second secretion in the culture supernatant of the stimulated cells, are shown for the Phase 1 study. Results for ELISPOT assays were described as spot forming cells per million for the Phase 2 study.

Both studies were designed to assess the safety, immunogenicity and efficacy (Phase 2 study only) of each individual vaccination regimen, and not for the support of inter-group comparisons. Only descriptive analysis was planned and the sample size was not statistically computed. Efficacy was assessed by comparison of malaria incidence and time to onset of parasitemia. Fisher’s Exact test was used for the comparison of malaria incidence between the control and each treated group. A Kaplan–Meier analysis was performed on time to onset of parasitemia, testing between the control and the two treatment groups using the log-rank statistic. The study flow for both trials is provided in Fig. 1. In the Phase 1 study, 40 subjects were enrolled and randomized (RTS,S/AS02 N = 10, TRAP/AS02 N = 10, RTS,S + TRAP/AS02 N = 20). The mean age of subjects was 34.3 years (range: 19–48 years), 60% were males and all were Caucasian. In the Phase 2 study, 43 subjects were enrolled (RTS,S + TRAP/AS02 N = 25, TRAP/AS02 N = 10, control N = 8).