Spatiotemporal dynamics and genotypic shift of Coxsackievirus A16 in Fujian, China, from 2010 to 2025

Abstract

Introduction Despite the diverse etiology of hand, foot, and mouth disease (HFMD), Coxsackievirus A16 (CVA16) persists as a dominant pathogen in the Asia-Pacific region. This study characterizes the molecular epidemiological evolution of CVA16 in Fujian Province from 2010 to 2025 to understand its changing prevalence and genetic evolution. Methods We analyzed the temporal, spatial, and demographic distributions of CVA16-HFMD in Fujian Province from 2010 to 2025, and further investigated the phylogenetic characteristics via MEGA and BEAST software. Results From 2010 to 2025, laboratory-confirmed CVA16 cases accounted for 25.96% of HFMD pathogen spectrum in Fujian, with periodic biennial fluctuations characterized by increases in even-numbered years and decreases in odd-numbered years and a post-2023 surged to >50%. CVA16 Cases peaked during spring–summer, with a male-to-female ratio of 1.69:1, predominantly in children aged 1–3 years. Genetically, B1 subgenotype (cluster B1a-c) co-circulated. B1b dominated before 2018, gradually shifting to B1a thereafter, and to B1c (emerging in late 2023) after mid-2023. Conclusion These findings clarify the long-term distribution and genetic shifts of CVA16 in Fujian, identifying the emerging B1c as a major driver of recent outbreaks and providing a baseline for regional HFMD prevention and vaccine development.