G6PD and G6PD deficiency: The optimal doses of the 8-aminoquinoline drugs (primaquine and tafenoquine) in the prevention of Plasmodium vivax relapse are a trade-off between the blood stage and hypnozoite effects (benefiting all patients), and the haemolytic risk in the sub-group of patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency.