Table 1 Strengths and limitations of this study

• The IMPROV Study is a multi-centre study in different regions providing evidence of primaquine tolerability across a variety of endemic settings.

• The long follow up (12 months) and continuation of follow up through multiple recurrences, allows estimation of the incidence density of all episodes, which is a better indicator of the overall morbidity of P. vivax relapse.

• A major challenge in estimating the efficacy of primaquine comes from our inability to distinguish relapses from new P. vivax infections. The control arm receiving the placebo is critical in providing provide comparative data from which to estimate the efficacy of the primaquine regimens.

• The trial assumes that a shorter course of primaquine will increase adherence and therefore effectiveness, however this not be tested directly in this clinical study