Lou Lishu, Zhang Longyao, Guan Jinxing, Ning Xiao, Nie Mengli, Wei Yongyue, Chen Feng
Department of Biostatistics, School of Public Health, Center of Global Health, Nanjing Medical University, Nanjing 211166, China.
Center for Public Health and Epidemic Preparedness & Response, Peking University, Xueyuan Road, Haidian District, Beijing 100191, China.
Trop Med Infect Dis. 2023 Jan 5;8(1):39. doi: 10.3390/tropicalmed8010039.
In late February 2022, the Omicron epidemic swept through Shanghai, and the Shanghai government responded to it by adhering to a dynamic zero-COVID strategy. In this study, we conducted a retrospective analysis of the Omicron epidemic in Shanghai to explore the timing and performance of control measures based on the eventual size and duration of the outbreak.
We constructed an age-structured and vaccination-stratified SEPASHRD model by considering populations that had been detected or controlled before symptom onset. In addition, we retrospectively modeled the epidemic in Shanghai from 26 February 2022 to 31 May 2022 across four periods defined by events and interventions, on the basis of officially reported confirmed (58,084) and asymptomatic (591,346) cases.
According to our model fitting, there were about 785,123 positive infections, of which about 57,585 positive infections were symptomatic infections. Our counterfactual assessment found that precise control by grid management was not so effective and that citywide static management was still needed. Universal and enforced control by citywide static management contained 87.65% and 96.29% of transmission opportunities, respectively. The number of daily new and cumulative infections could be significantly reduced if we implemented static management in advance. Moreover, if static management was implemented in the first 14 days of the epidemic, the number of daily new infections would be less than 10.
The above research suggests that dynamic zeroing can only be achieved when strict prevention and control measures are implemented as early as possible. In addition, a lot of preparation is still needed if China wants to change its strategy in the future.
2022年2月下旬，奥密克戎疫情席卷上海，上海市政府坚持动态清零策略应对疫情。在本研究中，我们对上海的奥密克戎疫情进行了回顾性分析，以根据疫情最终规模和持续时间探索防控措施的时机和效果。
我们构建了一个年龄结构和疫苗接种分层的SEPASHRD模型，考虑了症状出现前已被检测或管控的人群。此外，我们基于官方报告的确诊病例（58,084例）和无症状病例（591,346例），对2022年2月26日至2022年5月31日上海疫情在由事件和干预措施定义的四个时期进行了回顾性建模。
根据我们的模型拟合，约有785,123例阳性感染，其中约57,585例阳性感染为有症状感染。我们的反事实评估发现，网格化精准防控效果不佳，仍需全市静态管理。全市静态管理全面严格管控分别包含87.65%和96.29%的传播机会。如果提前实施静态管理，每日新增和累计感染数可显著减少。此外，如果在疫情最初14天实施静态管理，每日新增感染数将少于10例。
上述研究表明，只有尽早实施严格防控措施才能实现动态清零。此外，中国未来若要改变策略仍需大量准备工作。
