Dengue virus in Solomon Islands 2023-2025: a whole genome surveillance study

Background Following the cessation of COVID-19 travel restrictions in July 2022, concerns about a delayed dengue outbreak prompted the Solomon Islands Ministry of Health to establish enhanced genomic surveillance of circulating dengue virus (DENV) strains. Methods We performed amplicon-based whole genome sequencing (WGS) on PCR-positive serum samples collected at the National Referral Hospital, Honiara, between January 2023 and March 2025 (n = 63). Genomes were compared with publicly available sequences, and maximum-likelihood phylogenies were used to explore regional transmission dynamics. Findings We generated the first whole genome sequences from Solomon Islands (n = 45), with high recovery rates from acute infections (90%, Ct 17-44, mean coverage > 80%). Co-circulation of DENV-1, DENV-2, and DENV-4 was observed, with evidence of a serotype shift emerging in 2024. Phylogeographic analyses suggest ancestral introductions from Papua New Guinea for DENV-1 and DENV-2. Interpretation This study demonstrates the feasibility of whole genome sequencing for dengue surveillance in the Solomon Islands through a referral sequencing model that provides a pathway for progressive local capacity-building. By addressing technical challenges and critical gaps in regional genomic representation, our findings strengthen the evidence base needed for equitable and sustainable implementation of pathogen genomics across Pacific Island countries and territories.