JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
Department of Microbiology, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
BMJ Glob Health. 2020 Oct;5(10). doi: 10.1136/bmjgh-2020-003573.
An international city, Hong Kong, in proximity to the first epicentre of COVID- 19, experienced two epidemic waves with different importation pressure. We compared the epidemiological features of patients with COVID-19 in the context of containment policies between the first and second waves.
We retrieved information on the first 1038 cases detected in Hong Kong (23 January to 25 April 2020) to analyse the epidemiological characteristics including age/gender-specific incidence, clustering, reproduction number ( ) and containment delay; in relation to the containment measures implemented. Factors associated with containment delay were evaluated by multiple linear regression analysis with age, gender, epidemic wave and infection source as covariates. A time series of 5-day moving average was plotted to examine the changes across the two epidemic waves.
The incidence and mortality (135.5 and 0.5 per 1 000 000 population) was among the lowest in the world. Aggressive escalation of border control correlated with reductions in from 1.35 to 0.57 and 0.92 to 0.18, and aversions of 450 and 1650 local infections during the first and second waves, respectively. Implementing COVID-19 tests for overseas returners correlated with an upsurge of asymptomatic case detection, and shortened containment delay in the second wave. Medium-sized cluster events in the first wave were family gatherings, whereas those in the second wave were leisure activities among youngsters. Containment delay was associated with older age (adjusted OR (AOR)=1.01, 95% CI 1.00 to 1.02, p=0.040), male gender (AOR=1.41, 95% CI 1.02 to 1.96, p=0.039) and local cases (AOR=11.18, 95% CI 7.43 to 16.83, p<0.001), and with significant improvement in the second wave compared with the first wave (average: 6.8 vs 3.7 days). A higher incidence rate was observed for males, raising possibility of gender predilection in susceptibility of developing symptoms.
Prompt and stringent all-round containment strategies represent successful measures in pandemic control. These findings could inform formulation and implementation of pandemic mitigation strategies.
香港是一个国际化城市，毗邻 COVID-19 的首个疫情中心，经历了两波不同输入压力的疫情。我们比较了在第一波和第二波防控政策下 COVID-19 患者的流行病学特征。
我们检索了香港 2020 年 1 月 23 日至 4 月 25 日期间发现的前 1038 例病例的信息，分析了包括年龄/性别特定发病率、聚集性、繁殖数（）和防控延迟在内的流行病学特征；以及与实施的防控措施有关。采用多元线性回归分析，以年龄、性别、疫情波次和感染源为协变量，评估与防控延迟相关的因素。绘制 5 天移动平均时间序列，以检查两波疫情之间的变化。
香港的发病率和死亡率（每 100 万人口 135.5 和 0.5）为全球最低。边境管控的大力升级与从 1.35 降至 0.57 和从 0.92 降至 0.18 相关，分别避免了第一波和第二波本地感染 450 例和 1650 例。对海外返回者进行 COVID-19 检测与无症状病例检出率的上升相关，并缩短了第二波疫情的防控延迟。第一波中的中型聚集事件是家庭聚会，而第二波中的则是年轻人的休闲活动。防控延迟与年龄较大（调整后的 OR（AOR）=1.01，95%CI 1.00 至 1.02，p=0.040）、男性（AOR=1.41，95%CI 1.02 至 1.96，p=0.039）和本地病例（AOR=11.18，95%CI 7.43 至 16.83，p<0.001）有关，与第一波相比，第二波的防控延迟有显著改善（平均：6.8 天对 3.7 天）。男性的发病率较高，表明男性在出现症状的易感性方面可能存在性别倾向。
及时、严格的全面防控策略是控制大流行的成功措施。这些发现可为制定和实施大流行缓解策略提供参考。
