COVID-19 transmission driven by age-group mathematical model in Shijiazhuang City of China

Fengying Wei; Ruiyang Zhou; Zhen Jin; Senzhong Huang; Zhihang Peng; Jinjie Wang; Ximing Xu; Xinyan Zhang; Jun Xu; Yao Bai; Xiaoli Wang; Bulai Lu; Zhaojun Wang; Jianguo Xu

doi:10.1016/j.idm.2023.08.004

COVID-19 transmission driven by age-group mathematical model in Shijiazhuang City of China

Infect Dis Model. 2023 Aug 18;8(4):1050-1062. doi: 10.1016/j.idm.2023.08.004. eCollection 2023 Dec.

Authors

Fengying Wei^{1

2

3}, Ruiyang Zhou¹, Zhen Jin⁴, Senzhong Huang⁵, Zhihang Peng⁶, Jinjie Wang⁷, Ximing Xu⁸, Xinyan Zhang⁹, Jun Xu¹⁰, Yao Bai¹¹, Xiaoli Wang¹², Bulai Lu¹³, Zhaojun Wang¹⁰, Jianguo Xu^{14

15}

Affiliations

¹ School of Mathematics and Statistics, Fuzhou University, Fuzhou, 350116, Fujian, China.
² Center for Applied Mathematics of Fujian Province, Fuzhou University, Fuzhou, 350116, Fujian, China.
³ Key Laboratory of Operations Research and Control of Universities in Fujian, Fuzhou University, Fuzhou, 350116, Fujian, China.
⁴ Complex Systems Research Center, Shanxi University, Taiyuan, 030006, Shanxi, China.
⁵ School of Statistics and Data Science, ZhiYing Research Center for Health Data, Nankai University, 300071, Tianjin, China.
⁶ Department of Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, China.
⁷ Nankai Institute of Economics, Binhai Development Institute, Nankai University, Tianjin, 300071, China.
⁸ Children's Hospital of Chongqing Medical University, Chongqing, 400010, China.
⁹ Jinzhou Center for Disease Control and Prevention, Jinzhou, 121000, Liaoning, China.
¹⁰ School of Statistics and Data Science, Nankai University, Tianjin, 300071, China.
¹¹ Xi'an Center for Disease Control and Prevention, Xi'an, 710061, Shaanxi, China.
¹² Beijing Center for Disease Control and Prevention, Beijing, 100013, China.
¹³ Suzhou Center for Disease Control and Prevention, Suzhou, 215004, Jiangsu, China.
¹⁴ State Key Laboratory of Communicable Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, China.
¹⁵ Institute of Public Health, Nankai University, Tianjin, 300071, China.

Abstract

Background: A COVID-19 outbreak in the rural areas of Shijiazhuang City was attributed to the complex interactions among vaccination, host, and non-pharmaceutical interventions (NPIs). Herein, we investigated the epidemiological characteristics of all reported symptomatic cases by picking Shijiazhuang City, Hebei Province in Northern China as research objective. In addition, we established a with age-group mathematical model to perform the optimal fitting and to investigate the dynamical profiles under three scenarios.

Methods: All reported symptomatic cases of Shijiazhuang epidemic (January 2-February 3, 2021) were investigated in our study. The cases were classified by gender, age group and location, the distributions were analyzed by epidemiological characteristics. Furthermore, the reported data from Health Commission of Hebei Province was also analyzed by using an age-group mathematical model by two phases and three scenarios.

Results: Shijiazhuang epidemic caused by SARS-CoV-2 wild strain was recorded with the peak 84 cases out of 868 reported symptomatic cases on January 11, 2021, which was implemented with strong NPIs by local government and referred as baseline situation in this study. The research results showed that R₀ under baseline situation ranged from 4.47 to 7.72, and R_t of Gaocheng Distinct took 3.72 with 95% confidence interval from 3.23 to 4.35 on January 9, the declining tendencies of R_t under baseline situation were kept till February 3, the value of R_t reached below 1 on January 19 and remained low value up to February 3 for Gaocheng District and Shijiazhuang City during Shijiazhuang epidemic. This indicated Shijiazhuang epidemic was under control on January 19. However, if the strong NPIs were kept, but remote isolation operated on January 11 was not implemented as of February 9, then the scale of Shijiazhuang epidemic reached 9482 cases from age group who were 60 years old and over out of 31,017 symptomatic cases. The investigation also revealed that Shijiazhuang epidemic reached 132,648 symptomatic cases for age group who were 60 years old and over (short for G2) under risk-based strategies (Scenario A), 58,048 symptomatic cases for G2 under late quarantine strategies (Scenario B) and 207,124 symptomatic cases for G2 under late quarantine double risk strategies (Scenario C), and that the corresponding transmission tendencies of R_t for three scenarios were consistently controlled on Jan 29, 2021. Compared with baseline situation, the dates for controlling R_t below 1 under three scenarios were delayed 10 days.

Conclusions: Shijiazhuang epidemic was the first COVID-19 outbreak in the rural areas in Hebei Province of Northern China. The targeted interventions adopted in early 2021 were effective to halt the transmission due to the implementation of a strict and village-wide closure. However we found that age group profile and NPIs played critical rules to successfully contain Shijiazhuang epidemic, which should be considered by public health policies in rural areas of mainland China during the dynamic zero-COVID policy.

Keywords: COVID-19; Non-pharmaceutical interventions; Shijiazhuang epidemic; Transmission dynamics; Wild strain.