| Study | Reason for exclusion |
|---|---|
| Amador 1992 | Volunteers were randomized to two different groups, within each of which were vaccinees and controls; no randomization into vaccine and control groups |
| Gordon 1996 | Nonrandomized open label phase 1 trial; no placebo group |
| Migasena 1997 | Nonrandomized open label phase 1 study; no placebo group |
| Nosten 1997 | Open label phase 1 trial; no placebo group |
| Noya 1994 | Nonrandomized study |
| Patarroyo 1988 | Nonrandomized study |
| Patarroyo 1992 | Nonrandomized study, no placebo group |