目的 分析安徽省实施国家免疫规划吸附白喉-破伤风-无细胞百日咳疫苗（diphtheria-tetanus-acellular pertussis vaccine，DTaP）新免疫策略前后的疑似预防接种异常反应（adverse event following immunization，AEFI）发生情况和分布特征，为新免疫策略的安全性评估提供依据。方法 收集中国疾病预防控制中心免疫规划信息管理系统中安徽省2024年（策略调整前）和2025年（自1月1日起实施新策略，即策略调整后）的AEFI监测数据，从安徽省免疫规划信息管理系统获取同期DTaP接种剂次数。采用描述性流行病学方法分析DTaP AEFI的分布特征及发生率，采用χ²检验或Fisher确切概率法比较策略调整前后的差异。结果 2024—2025年安徽省共接种DTaP 2 375 028剂，报告AEFI 4 958例，总发生率为208.76/10万剂。策略调整后，一般反应发生率由186.69/10万剂上升至221.37/ 10万剂（χ²=32.50，P<0.001）；异常反应发生率由0.66/10万剂下降至0.20/10万剂，降幅约69.70%。首剂接种年龄提前至2月龄后，第1剂次的AEFI发生率由170.57/10万剂降至119.65/10万剂（χ²=24.76, P<0.001）；6周岁剂次由白喉-破伤风疫苗调整为DTaP后，未监测到异常反应病例，发生率0.00/10万剂（95% 置信区间: 0.00~0.83/10万剂）。结论 安徽省DTaP AEFI以一般反应为主，异常反应报告率极低。免疫策略调整后首剂提前至2月龄明显降低了AEFI发生率，有利于尽早建立免疫屏障；6周岁加强剂次改用DTaP后未监测到异常反应，表明本研究观察期内核心安全性指标表现良好。2、4、6、18月龄及6岁接种5剂次DTaP的新策略在本研究观察期内显示出较好的安全性。

Objective To analyze the incidence and distribution characteristics of adverse events following immunization (AEFIs) associated with diphtheria-tetanus-acellular pertussis vaccine (DTaP) before and after the implementation of new immunization strategy under the National Immunization Program in Anhui Province, and to provide evidence for evaluating the safety of the new strategy.Methods AEFI surveillance data in Anhui Province during 2024（before strategy adjustment） to 2025（after the new strategy implemention on January 1, 2025） were collected through the Immunization Program Information Management System of the Chinese Center for Disease Control and Prevention, and concurrent vaccination data were obtained from Anhui Immunization Program Information Management System. Descriptive epidemiological methods were used to analyze the distribution and incidence of AEFI. The Chi-square test or Fisher’s precision probability test were used to compare the data before and after the policy adjustment.Results From 2024 to 2025, a total of 2 375 028 doses of DTaP were administered in Anhui Province, with 4 958 AEFI cases reported. The overall incidence was 208.76/100 000 doses. Following the strategy adjustment, the incidence of general reactions increased from 186.69/100 000 doses to 221.37/100 000 doses (χ²=32.50, P<0.001)，while the incidence of adverse reactions (rare/serious) decreased from 0.66/100 000 doses to 0.20/100 000 doses, representing a reduction of approximately 69.70%. After advancing the first dose to 2 months of age, the AEFI incidence decreased from 170.57/100 000 doses to 119.65/100 000 doses (χ²=24.76, P<0.001). For the 6-year-old dose switched from the diphtheria and tetanus vaccine to DTaP, no adverse reactions were observed, with incidence of 0.00/100 000 doses (95% confidence interval: 0.00-0.83/100 000 doses ).Conclusions DTaP AEFIs in Anhui Province are predominantly general reactions, with extremely low adverse reaction rates. Advancing the first dose to 2 months of age significantly reduces the AEFI incidence, facilitating the early establishment of immune barrier. With no new safety risks monitored during this surveillance period after switching to DTaP for the 6-year-old booster, core safety indicators perform well during the study period. The new 5-dose DTaP strategy (at 2, 4, 6, 18 months and 6 years of age) demonstrates a good safety profile within the observation period.