The Southeast Asia Dose Optimisation of Tafenoquine (SEADOT) study aims to optimise single-dose tafenoquine for P. vivax radical cure in regions with short latency relapse. Adults and children at least 2 years old weighing at least 10 kg with P. vivax malaria are recruited and followed for 4 months. The study is being conducted in Cambodia, Lao PDR, Thailand, and Vietnam.