Table 1.
VE against homologous CHMI
| # Completing CHMI per protocol | Median time from last vaccine dose to CHMI (range) | # Without parasitemia at 28 days by | VE by qPCR* | |||
|---|---|---|---|---|---|---|
| TBS | qPCR | |||||
| PfSPZ Vaccine | Group 1 (1, 3, 5, 7, 113) | 17 | 52 days | 12 | 10 (58.8%) | 39.8% (P = 0.13) |
| Group 2 (1, 3, 5, 7) | 21 | 46 days (42–46 days) | 11 | 11 (52.4%) | 30.4% (P = 0.22) | |
| Group 3 (1, 3, 5, 7, 29) | 18†‡ | 42 days | 8 | 7 (38.9%) | 10.7% (P = 0.74) | |
| Group 4 (1, 8, 29) | 21 | 48 days | 14 | 14 (66.7%) | 51.3% (P = 0.03) | |
| Controls | Pooled | 19 | – | 12 | 6 (31.6%) | – |
| Total | 96 | 57 | 48 | |||
CHMI = controlled human malaria infection; qPCR = quantitative polymerase chain reaction; TBS = thick blood smear; VE = vaccine efficacy.
*
VE calculated as VE = one-risk ratio. P values calculated using Barnard’s test, two-tailed.
†
One subject withdrew from inpatient observation on day CHMI+10 for personal reasons, was treated and was not included in VE calculations or counted in the 18 completing CHMI.
‡
One subject was unintentionally treated with single dose of AL on day CHMI+18. This subject remained negative throughout the duration of CHMI follow-up but was not included in VE calculations or counted in the 18 completing CHMI.