Objective  To evaluate the impact of non-pharmaceutical interventions (NPIs) on the incidence of notifiable infectious disease in Jingzhou of Hubei province.

  Methods  The weekly incidence of notifiable infectious disease in Jingzhou from December 29, 2014 (1^st week in 2015) to January 3, 2021 (53^rd week in 2020) was collected. The 1st week of 2015 to the 5th week of 2020 was used to fit a Bayesian structural time series (BSTS) model and predict the incidence of notifiable infectious disease from 6^th to 53^rd weeks in 2020. The incidence of notifiable infectious disease from 6^th week to 53^rd week in 2020 was compared with those during the same periods of 2015−2019 and the predicted value of the BSTS model in 2020, and the relative reduction (RR) was used to evaluate the impact of NPIs on the incidence of notifiable infectious disease. Disease types, gender, age groups, disease classification (class A, B and C; respiratory infectious diseases, intestinal infectious diseases, blood-borne and sexually transmitted infections, natural focal diseases), and periods (6^th−18^th week, 19^th−24^th week, 25^th−53^rd week) were used for subgroup analysis.

  Results  A total of 18 952 cases of 20 types of notifiable infectious diseases were reported in Jingzhou from 6^th week to 53^rd week in 2020, a decrease of 45.26% compared with the same periods during 2015− 2019. Based on the BSTS model, a decrease of 60.42% was than expected during 6^th week−53^rd week of 2020 (95% CI: 50.98%–69.66%). The notifiable infectious diseases in class A and B and in class C decreased by 36.63% (95% CI: 30.60%–43.19%) and 60.72% (95% CI: 33.97%–85.32%), respectively. The incidence of notifiable infectious disease during 6^th week−18^th week, 19^th week−24^th week, and 25^th week−53^rd week in 2020 decreased by 70.29% (95% CI: 56.88%–83.29%), 61.71% (95% CI: 45.34%–79.13%), 55.68% (95% CI: 45.60%–67.29%) respectively. In terms of transmission routes, the incidence of respiratory infectious disease had the greatest decrease (RR=61.53%, 95% CI: 22.60%–100.87%), followed by intestinal infectious disease (RR=19.72%, 95% CI: 2.98%–35.29%). In terms of age, the largest decrease was found for people aged 15–64 years (RR=72.74%, 95% CI: 65.68%–80.10%), followed by children aged 0–14 years (RR=54.51%, 95% CI: 19.78%–87.15%). There was a positive correlation between the incidence of COVID-19 and the incidence decrease in different areas in 2020 ( r_s =0.714, P=0.058). The top 5 diseases with the largest incidence decrease were rubella (999.77%, 95% CI: −2326.82%–4510.97%), influenza (68.93%, 95% CI: 91.76%–117.10%), scarlet fever (88.59%, 95% CI: 64.78%–112.12%), hand foot and mouth disease (86.09%, 95% CI: 77.46%–94.55%) and acute hemorrhagic conjunctivitis (78.54%, 95% CI: 28.11%–127.26%).

  Conclusion  The NPIs against COVID-19 could significantly reduce the incidence of notifiable infectious disease in Jingzhou, and its effect had heterogeneity in terms of population, disease, time and space.