Objective To analyze the epidemiological trend and spatiotemporal distribution characteristics of hepatitis C incidence in the mainland of China from 2004 to 2020, thereby providing a scientific basis for precise prevention and control.

Methods Data were obtained from the China Public Health Science Data Center, covering reported hepatitis C cases and incidence rates across 31 provinces (autonomous regions and municipalities) from January 1, 2004 to December 31, 2020. The Joinpoint regression model was adopted to analyze the temporal trends by calculating the average annual percent change (AAPC) and annual percent change (APC), and the Bayesian spatiotemporal model proposed by Bernardinelli was employed to assess the spatiotemporal evolutionary characteristics of hepatitis C.

Results From 2004 to 2020, the average annual incidence of hepatitis C in the mainland of China was 11.67 per 100 000, with yearly rates of 3.03, 4.07, 5.41, 7.03, 8.21, 9.93, 11.47, 12.97, 14.96, 15.00, 14.97, 15.26, 15.09, 15.51, 15.79, 16.02, and 13.82 per 100 000, respectively, showing an overall increasing trend (AAPC = 10.15%, 95%CI: 9.73%–10.64%). Significant upward trends were observed during 2004–2007 (APC = 33.17%, 95%CI: 29.75%–39.81%), 2008–2012 (APC = 15.79%, 95%CI: 14.03%–17.99%), and 2013–2018 (APC = 0.89%, 95%CI: 0.06%–5.08%), whereas a decline occurred during 2019–2020 (APC = –4.82%, 95%CI: –7.47% to –0.83%). Regional disparities were evident, with Xinjiang Uygur Autonomous Region (551.51/100 000), Qinghai province (453.22/100 000), and Gansu province (430.73/100 000) exhibiting the highest average annual incidences, Xizang Autonomous Region showing the largest increase (AAPC = 26.40%, 95%CI: 21.32%–32.29%), and Beijing demonstrating a declining trend (APC = –3.93%, 95%CI: –5.91% to –0.74%). The Bayesian spatiotemporal model proposed by Bernardinelli indicated that the relative risk (RR) of hepatitis C across the mainland of China from 2004 to 2020 ranged from 0.012 to 4.248. Higher and more fluctuating RR values were observed in northwestern regions (including Xinjiang Uygur Autonomous Region, Qinghai province, and Gansu province), whereas southeastern coastal provinces (e.g., Zhejiang, Jiangsu), parts of northern China (e.g., Tianjin and Beijing), and southwestern regions (e.g., Xizang Autonomous Region) showed lower and more stable RR values. The RR values of most provincial-level administrative regions, such as Gansu province, Henan province, and Jilin province, displayed a rise–fall pattern, steadily increasing after 2004, peaking between 2013 and 2016, and then decreasing, while Yunnan province, Hunan province, and Sichuan province exhibited a continuous upward trend throughout the study period.

Conclusion Between 2004 and 2020, the overall incidence of hepatitis C in the mainland of China exhibited an upward trend, with significant temporal and spatial variations. High-risk areas were concentrated in northwestern China, while certain provincial-level administrative regions in southwestern China showed marked increases in the incidence.