Zika virus in the Americas: transmission dynamics, clinical lessons, and future risk.

INTRODUCTION: The emergence of Zika virus (ZIKV) in the Americas between 2015 and 2016 transformed a previously neglected arbovirus into a major global public health concern, revealing the consequences of congenital infection and neurological disease while exposing critical weaknesses in surveillance and response capacity. Although epidemic transmission has substantially declined, ZIKV continues to circulate at low levels across several regions of the Americas, and the risk of future resurgence remains uncertain. AREAS COVERED: In this review, we synthesize current evidence on the epidemiology, transmission dynamics, molecular evolution, and clinical impact of ZIKV in the Americas, integrating findings from clinical, epidemiological, and genomic studies. We discuss how phylogenetic and phylogeographic analyses have reconstructed viral spread, uncovered prolonged cryptic transmission before outbreak recognition, and clarified the roles of human mobility, vector ecology, and population immunity in shaping epidemic dynamics. We also examine persistent diagnostic and surveillance challenges. EXPERT OPINION: Despite the marked decline in reported ZIKV transmission since the 2015-2016 epidemic, continued low-level circulation and substantial surveillance gaps mean that the potential foM. Giovanetti is supported by the Novo Nordisk Foundation (NNF24OC0094346). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.r future resurgence should not be underestimated. Integrated genomic, entomological, epidemiological, and clinical surveillance will be essential for earlier detection of changes in transmission, improved characterization of viral spread, and more timely public health responses. Strengthening these systems will also provide broader preparedness benefits for other emerging and reemerging arboviruses.