Interventions to mitigate early spread of SARS-CoV-2 in Singapore: a modelling study
Interventions to mitigate early spread of SARS-CoV-2 in Singapore: a modelling study
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DOI：
10.1016/s1473-3099(20)30162-6
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发表时间：
2020-06-01
影响因子：
56.3
通讯作者：
Dickens, Borame L.
中科院分区：
文献类型：
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作者：
Koo, Joel R.;Cook, Alex R.;Dickens, Borame L.
自2019年12月31日中国武汉市爆发2019年冠状病毒病以来，新加坡已报告68例输入性病例和175例本地获得性感染。我们的目的是探讨在新加坡的早期干预方案，应当地遏制（例如，通过接触追踪工作，防止疾病传播）是successful.Methods我们适应了流感流行模拟模型，以估计人与人之间传播的可能性严重急性呼吸系统综合征冠状病毒2（SARS-CoV-2）在模拟新加坡人口。使用该模型，我们估计了在检测到100例社区传播后80天的SARS-CoV-2感染的累积数量，在三种传染性情景下（基本繁殖数[R-0]为1.5，2.0或2.5），并假设7.5%的感染是无症状的。我们首先运行模型，假设没有干预措施（基线情景），然后评估四种干预情景与基线情景相比对每个R-0值的爆发规模和进展的影响。这些方案包括对受感染者采取隔离措施和家庭成员隔离（以下简称隔离）;隔离加学校关闭;隔离加工作场所隔离;以及隔离、学校关闭和工作场所隔离（以下简称综合干预）。我们还通过改变无症状感染比例进行了敏感性分析（22.7%、30.0%、40.0%和50.0%）比较相同控制措施下的爆发规模。结果对于基线情景，当R 0为1.5时，第80天的中位累积感染数为279000（IQR 245 000-320 000），相当于新加坡常住人口的7.4%（IQR 6.5-8.5）。感染的中位数随着感染性的增加而增加：727 000例当R-0为2.0时，（670 000-776 000），相当于19.3%（17.8-20.6），当R-0为2.5时为1207000例（1164000 - 1249000），相当于新加坡人口的32%（30.9-33.1）。与基线方案相比，联合干预最有效，当R-0为1.5时，估计的中位感染数减少了99.3%（IQR 92.6-99.9），当R-0为2.0时，减少了93.0%（81.5-99.7），当R-0为2.5时，减少了78.2%（59.0 - 94.4）。假设无症状分数增加至50.0%，则在R-0为1.5时，相对于基线的1800例联合干预，估计在第80天发生多达277000例感染。解释实施预防感染者及其家人，工作场所距离，一旦发现社区传播，关闭学校可以大大减少SARS-CoV-2感染的数量。因此，我们建议，如果在新加坡境内确认出现本地二次传播，立即部署这一战略。然而，隔离和工作场所的距离应优先于学校关闭，因为在这个早期阶段，有症状的儿童从学校退学的比例高于有症状的成年人。在无症状比例较高的情况下，干预的有效性可能会大大降低，需要有效的病例管理和治疗，以及疫苗等预防措施。
Background Since the coronavirus disease 2019 outbreak began in the Chinese city of Wuhan on Dec 31, 2019, 68 imported cases and 175 locally acquired infections have been reported in Singapore. We aimed to investigate options for early intervention in Singapore should local containment (eg, preventing disease spread through contact tracing efforts) be unsuccessful.Methods We adapted an influenza epidemic simulation model to estimate the likelihood of human-to-human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a simulated Singaporean population. Using this model, we estimated the cumulative number of SARS-CoV-2 infections at 80 days, after detection of 100 cases of community transmission, under three infectivity scenarios (basic reproduction number [R-0] of 1.5, 2.0, or 2.5) and assuming 7.5% of infections are asymptomatic. We first ran the model assuming no intervention was in place (baseline scenario), and then assessed the effect of four intervention scenarios compared with a baseline scenario on the size and progression of the outbreak for each R-0 value. These scenarios included isolation measures for infected individuals and quarantining of family members (hereafter referred to as quarantine); quarantine plus school closure; quarantine plus workplace distancing; and quarantine, school closure, and workplace distancing (hereafter referred to as the combined intervention). We also did sensitivity analyses by altering the asymptomatic fraction of infections (22.7%, 30.0%, 40.0%, and 50.0%) to compare outbreak sizes under the same control measures.Findings For the baseline scenario, when R 0 was 1.5, the median cumulative number of infections at day 80 was 279 000 (IQR 245 000-320 000), corresponding to 7.4% (IQR 6.5-8.5) of the resident population of Singapore. The median number of infections increased with higher infectivity: 727 000 cases (670 000-776 000) when R-0 was 2.0, corresponding to 19.3% (17.8-20.6) of the Singaporean population, and 1 207 000 cases (1 164 000-1 249 000) when R-0 was 2.5, corresponding to 32% (30.9-33.1) of the Singaporean population. Compared with the baseline scenario, the combined intervention was the most effective, reducing the estimated median number of infections by 99.3% (IQR 92.6-99.9) when R-0 was 1.5, by 93.0% (81.5-99.7) when R-0 was 2.0, and by 78.2% (59.0 -94.4) when R-0 was 2.5. Assuming increasing asymptomatic fractions up to 50.0%, up to 277 000 infections were estimated to occur at day 80 with the combined intervention relative to 1800 for the baseline at R-0 of 1.5.Interpretation Implementing the combined intervention of quarantining infected individuals and their family members, workplace distancing, and school closure once community transmission has been detected could substantially reduce the number of SARS-CoV-2 infections. We therefore recommend immediate deployment of this strategy if local secondary transmission is confirmed within Singapore. However, quarantine and workplace distancing should be prioritised over school closure because at this early stage, symptomatic children have higher withdrawal rates from school than do symptomatic adults from work. At higher asymptomatic proportions, intervention effectiveness might be substantially reduced requiring the need for effective case management and treatments, and preventive measures such as vaccines.