State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China.
Department of Infectious Disease, Haihe Clinical School, Tianjin Medical University, Tianjin, China.
BMJ Open. 2022 Dec 15;12(12):e066359. doi: 10.1136/bmjopen-2022-066359.
To report how the Chinese mainland battled its first omicron wave, which happened in Tianjin, a metropolis with 14 million residents. We also sought to better understand how clinical features affected the timing of viral clearance.
A retrospective study of the omicron wave in Tianjin between 8 January 2022 and 3 March 2022.
Except for the first cases on 8 January, all the omicron cases were identified through PCR mass testing in the residential communities. Residential quarantine and serial PCR mass testing were dynamically adjusted according to the trends of new cases.
All the 417 consecutive PCR-positive cases identified through mass screening of the entire city's 14 million residents. 45.3% of the cases were male, and the median age was 37 (range 0.3-90). 389 (93%) cases had complete data for analysing the correlation between clinical features and the timing of viral clearance.
Time to viral clearance.
Tianjin initiated the 'dynamic zero-COVID' policy very early, that is, when daily new case number was ≈0.4 cases per 1 000 000 residents. Daily new cases dropped to <5 after 3 February, and the number of affected residential subdivisions dropped to ≤2 after 13 February. 64% (267/417) of the cases had no or mild symptoms. The median interval from hospital admission to viral clearance was 10 days (range 3-28). An exploratory analysis identified a feature cluster associated with earlier viral clearance, with HRs of 3.56 (95% CI 1.66 to 7.63) and 3.15 (95% CI 1.68 to 5.91) in the training and validation sets, respectively.
The 'dynamic zero-COVID' policy can suppress an omicron wave within a month. It might be possible to predict in advance which cases will require shorter periods of isolation based on their clinical features.
报告中国大陆如何应对首次在拥有 1400 万居民的特大城市天津发生的奥密克戎疫情。我们还试图更好地了解临床特征如何影响病毒清除的时间。
2022 年 1 月 8 日至 2022 年 3 月 3 日期间对天津奥密克戎疫情进行的回顾性研究。
除了 1 月 8 日的首例病例外，所有奥密克戎病例都是通过居民区的 PCR 大规模检测发现的。根据新病例的趋势，动态调整居家隔离和连续 PCR 大规模检测。
对全市 1400 万居民进行大规模筛查发现的 417 例连续 PCR 阳性病例。45.3%的病例为男性，中位年龄为 37 岁（范围为 0.3-90 岁）。389 例（93%）病例的临床特征与病毒清除时间的相关性分析数据完整。
病毒清除时间。
天津很早就启动了“动态清零”政策，即当每日新增病例数约为每 100 万居民 0.4 例时。每日新增病例数在 2 月 3 日降至<5 例以下，受影响的居民区数量在 2 月 13 日降至≤2 个。64%（267/417）的病例无症状或症状较轻。从住院到病毒清除的中位间隔为 10 天（范围为 3-28 天）。一项探索性分析确定了一个与更早病毒清除相关的特征簇，在训练集和验证集中，HR 分别为 3.56（95%CI 1.66-7.63）和 3.15（95%CI 1.68-5.91）。
“动态清零”政策可以在一个月内抑制奥密克戎疫情。根据临床特征，有可能提前预测哪些病例需要更短的隔离期。
