Application of moving epidemic method in evaluation of influenza epidemic intensity in Zhejiang Province from 2012 to 2023
FENG Yan1, XU Zenghao1, LING Feng2, JIN Jialie1, WANG Xiaoxiao1, SHANG Xiaopeng2, SUN Jimin1
1. Department of Communicable Disease Control and Prevention, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang 310051, China; 2. Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang 310051, China
Abstract：Objective To estimate the epidemic threshold and graded intensity thresholds of influenza in Zhejiang Province from 2012 to 2023 using the moving epidemic method (MEM), and evaluate the intensity of influenza epidemics, so as to provide the reference for influenza prevention and control in Zhejiang Province. Methods The positive rates of influenza virus per week during the influenza epidemic seasons (from 40th week to 20th week of the following year) in Zhejiang Province from 2012 to 2022 were collected through the Chinese Influenza Surveillance Information System. A MEM model was established and optimized using cross-validation. The maximum accumulated rates percentage was used to divide the epidemic into pre-epidemic, epidemic, and post-epidemic periods, and to estimate the epidemic thresholds and graded intensity thresholds. The intensity of influenza epidemics in Zhejiang Province during the 2022-2023 epidemic season were assessed. Results The positive rates of influenza virus in five epidemic seasons from 2012 to 2022 were included in the model. The MEM model performed best when the parameter δ was set to 1.5, with a sensitivity of 0.971, a specificity of 0.745, and a Youden's index of 0.716. According to the model analysis, the epidemic beginning and ending thresholds of influenza in Zhejiang Province during the 2022-2023 epidemic season were 19.32% and 10.92%, respectively, and the medium, high, and extremely high intensity thresholds were 48.65%, 63.49%, and 68.47%, respectively. During 2022-2023, the influenza epidemic was in the pre-epidemic period from the 40th week in 2022 to the 7th week in 2023; the epidemic period was from the 8th to the 18th week, the epidemic intensity was low in the 8th week and increased to a high level in the 9th week, and reached to a extremely high level from the 10th to the 13th week, then fell to the high and the medium level in the 14th week and 15th week, respectively, and fell to a low level from the 16th to the 18th week; the influenza epidemic entered the post-epidemic period since the 19th week. Conclusion MEM could be applied for evaluation of influenza epidemic intensity, providing the reference for early identification and taking graded preventive and control measures.
丰燕, 徐增豪, 凌锋, 金家列, 王笑笑, 尚晓鹏, 孙继民. 应用移动流行区间法分析2012—2023年浙江省流行性感冒流行强度[J]. 预防医学, 2024, 36(10): 829-833.
FENG Yan, XU Zenghao, LING Feng, JIN Jialie, WANG Xiaoxiao, SHANG Xiaopeng, SUN Jimin. Application of moving epidemic method in evaluation of influenza epidemic intensity in Zhejiang Province from 2012 to 2023. Preventive Medicine, 2024, 36(10): 829-833.
