Renewed efforts to eliminate malaria have had greater impact on Plasmodium falciparum AU : Pleasenotethatasp than Plasmodium vivax, a reflection of the fundamental differences in the biology of the parasite, its transmission dynamics, and ability to form dormant liver stages. • The main burden of P. vivax malaria is in young children residing in remote communities with poor access to healthcare services. • The decline in P. vivax malaria has led to an increasing proportion of the parasite reservoir occurring in asymptomatic and low-density P. vivax infections and heterogeneous patterns of parasite transmission. • Genetic tools to study the spatial and temporal patterns of P. vivax transmission in different endemicities and ultrasensitive PCR (uPCR)-based techniques are expanding our knowledge of the magnitude and biology of low-density P. vivax infections. • Serology offers alternative ways of detecting recent P. vivax infections and monitoring of the impact of public health interventions at very low endemicity.