Epidemiological Characteristics of Coxsackievirus A6 in Baotou, Inner Mongolia, China, 2023-2024

The re-emergence of Coxsackievirus A6 (CV-A6) as a predominant pathogen in hand, foot, and mouth disease (HFMD) underscores the need for ongoing molecular surveillance to clarify local evolutionary dynamics. This study aimed to characterize the genetic features of CV-A6 strains circulating in Baotou, Inner Mongolia, from 2023 to 2024. Throat swabs collected from HFMD patients were screened using real-time quantitative PCR; the VP1 region and complete genomes of representative CV-A6-positive samples were amplified and sequenced. Phylogenetic and recombination analyses were subsequently performed. Among 266 clinical specimens, 169 (63.53%) tested positive for enterovirus, of which 146 (86.39%) were identified as CV-A6. The local epidemic displayed an autumn-winter seasonality and predominantly affected children aged 4-6 years. Phylogenetic reconstruction of 133 VP1 sequences revealed that all Baotou CV-A6 isolates belonged to subgenotype D3c, and analysis of complete genomes identified a predominant recombinant form. These findings demonstrate that the D3c subgenotype, characterized by a specific recombinant structure, was responsible for HFMD outbreaks in Baotou during the study period, providing essential molecular evidence for regional public health strategies and vaccine development.