This paper analyzes the heterogeneity and effectiveness of COVID-19 prevention and control measures in 25 major Chinese cities from January 11 to February 10, 2020. Using a time-varying reproduction number method and a serial correlation method, the study finds that while the effective reproduction number (R) showed an overall downward trend, significant differences existed among cities. 21 out of 25 cities effectively controlled the epidemic (R < 1 by February 10th), while Wuhan, Tianmen, Ezhou, and Enshi still faced challenges. The study identifies critical time points for outbreak control in various cities and offers insights for improving epidemic prevention and control measures.
