The spatiotemporal analysis of SARS-CoV-2 transmission in China since the termination of the dynamic zero-COVID policy.

ABSTRACT

China's dynamic zero-COVID policy has effectively curbed the spread of SARS-CoV-2, while inadvertently creating immunity gaps within its population. Subsequent surges in COVID-19 cases linked to various SARS-CoV-2 lineages post-policy termination necessitate a thorough investigation into the epidemiological landscape. This study addresses this issue by analyzing a comprehensive dataset of 39,456 high-quality genomes collected nationwide over an 11-month period since policy termination. Through lineage assignment, phylogenetic analysis, pandemic pattern comparison, phylodynamic reconstruction, and recombination detection, we found that China's post-epidemic period could be divided into three stages, along with dynamic changes in dominant lineages. Geographical clustering of similar lineages implies the importance of cross-border cooperation among neighboring regions. Compared to the USA, UK, and Japan, China exhibits unique trajectories of lineage epidemics, characterized by initial lagging followed by subsequent advancement, indicating the potential influence of diverse prevention and control policies on lineage epidemic patterns. Hong Kong, Shanghai, and Hubei emerge as pivotal nodes in the nationwide spread, marking a shift in the transmission center from east to central regions of China. Although China hasn't experienced significant variant emergence, the detection and validation of the novel recombination event, XCN lineage, underscore the ongoing virus evolution. Overall, this study systematically analyzes the spatiotemporal transmission of SARS-CoV-2 virus in China since the termination of the dynamic zero-COVID policy, offering valuable insights for regional surveillance and evidence-based public health policymaking.