Quantifying the impact of physical distance measures on the transmission of COVID-19 in the UK
Quantifying the impact of physical distance measures on the transmission of COVID-19 in the UK
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DOI：
10.1186/s12916-020-01597-8
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发表时间：
2020-05-07
期刊：
影响因子：
9.3
通讯作者：
Edmunds, W. John
中科院分区：
文献类型：
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作者：
Jarvis, Christopher I.;Van Zandvoort, Kevin;Edmunds, W. John
背景为减轻及减缓COVID-19的传播，包括英国在内的多个国家已采取前所未有的物理距离政策。我们评估这些措施是否足以控制流行病，通过估计其对繁殖数量的影响（R-0，每个病例产生的继发病例的平均数量）。方法我们询问了英国成年人的代表性样本，询问他们在前一天的接触模式。调查问卷是通过电子邮件招募在线进行的，记录了联系人的年龄和地点以及他们的亲密程度（无论是否有身体接触）。此外，我们还询问了对不同物理距离措施的遵守情况。第一批调查是在3月24日星期二，即英国全境实施“封锁”后的第一天发送的。我们比较了“封锁”期间测量的接触模式与非流行时期的社会接触模式。通过比较这些，我们估计的结果，实施物理距离措施的繁殖数量的变化。我们使用了对已发表估计值的荟萃分析，以告知我们在干预措施到位之前对生殖数量的估计。结果我们发现每个参与者的平均每日接触次数减少了74%（从10.8减少到2.8）。这足以将R-0从锁定前的2.6降低至锁定后的0.62（95%置信区间[CI] 0.37-0.89）（基于所有类型的接触）和0.37（95% CI = 0.22-0.53）（仅针对物理（皮肤与皮肤）接触）。英国公众采取的物理距离措施大大降低了接触水平，并可能在未来几周内产生重大影响和病例下降。然而，这种预计的发病率下降不会立即发生，因为感染、症状性疾病发作和住院治疗之间存在显著延迟，以及报告这些事件的进一步延迟。跟踪行为变化可以比常规流行病学监测更迅速地评估实际距离措施的影响。
Background To mitigate and slow the spread of COVID-19, many countries have adopted unprecedented physical distancing policies, including the UK. We evaluate whether these measures might be sufficient to control the epidemic by estimating their impact on the reproduction number (R-0, the average number of secondary cases generated per case). Methods We asked a representative sample of UK adults about their contact patterns on the previous day. The questionnaire was conducted online via email recruitment and documents the age and location of contacts and a measure of their intimacy (whether physical contact was made or not). In addition, we asked about adherence to different physical distancing measures. The first surveys were sent on Tuesday, 24 March, 1 day after a "lockdown" was implemented across the UK. We compared measured contact patterns during the "lockdown" to patterns of social contact made during a non-epidemic period. By comparing these, we estimated the change in reproduction number as a consequence of the physical distancing measures imposed. We used a meta-analysis of published estimates to inform our estimates of the reproduction number before interventions were put in place. Results We found a 74% reduction in the average daily number of contacts observed per participant (from 10.8 to 2.8). This would be sufficient to reduce R-0 from 2.6 prior to lockdown to 0.62 (95% confidence interval [CI] 0.37-0.89) after the lockdown, based on all types of contact and 0.37 (95% CI = 0.22-0.53) for physical (skin to skin) contacts only. Conclusions The physical distancing measures adopted by the UK public have substantially reduced contact levels and will likely lead to a substantial impact and a decline in cases in the coming weeks. However, this projected decline in incidence will not occur immediately as there are significant delays between infection, the onset of symptomatic disease, and hospitalisation, as well as further delays to these events being reported. Tracking behavioural change can give a more rapid assessment of the impact of physical distancing measures than routine epidemiological surveillance.