Abstract: Objective To understand the change of rubella incidence before and after the expanded program on immunization （EPI） in Hebei Province and give short‐term and long‐term evaluation of its preventive effect. Methods The incidence of rubella report in Hebei Province from 2004 to 2022 was collected,and a multiple linear regression model was established by interrupted time series analysis. According to the slope and coefficient,the effect of the EPI was evaluated. Results From 2004 to 2022,a total of 25 690 cases of rubella were reported,the reported annual average incidence was 1.925/100 000,accounting for 1.00% of the reported incidence of Class C infectious diseases. Results of interrupted time series regression model analysis indicated an increasing incidence of rubella reports before EPI in 2004-2008 （β₁=0.004 3,P<0.05）. In 2009,for the first year after the EPI,the short‐term intervention worked well,reported a decrease in incidence from previously. A decrease in incidence was reported in the post‐EPI phase from 2009 to 2022 （β₃=-0.005 6,P<0.05）. There was an overall downward trend in reported incidence after EPI （β₁+β₃=-0.001 3）. The reported annual average incidence decreased from 3.938/100 000 before EPI to 1.206/100 000 after EPI. Conclusions The use of interrupted time series regression model to evaluate the efficacy of rubella before and after the implementation of EPI can be extruded to other infectious diseases or diseases. It can provide new methods and ideas for professionals.

Key words: Interrupted time series, Immunization planning, Prevention and control, Effect, Evaluation