The basic reproduction number, R₀, and its real-time analogue, R_t, are summary measures that reflect the ability of an infectious disease to spread through a population. Estimation methods for R_t have a long history, have been widely developed and are now enhanced by application to the COVID-19 pandemic. While retrospective analyses of R_t have provided insight into epidemic dynamics and the effects of control strategies in prior outbreaks, misconceptions around the interpretation of R_t have arisen with broader recognition and near real-time monitoring of this parameter alongside reported case data during the COVID-19 pandemic. Here, we discuss some widespread misunderstandings regarding the use of R_t as a barometer for population risk and its related use as an ‘on/off’ switch for policy decisions regarding relaxation of non-pharmaceutical interventions. Computation of R_t from downstream data (e.g. hospitalizations) when infection counts are unreliable exacerbates lags between when transmission happens and when events are recorded. We also discuss analyses that have shown various relationships between R_t and measures of mobility, vaccination coverage and a test–trace–isolation intervention in different settings.

中文翻译：

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关于 SARS-CoV-2 繁殖数的使用：估计、误解以及与其他生态措施的关系

基本再生数R ₀及其实时类似物R _t是反映传染病在人群中传播能力的概括性度量。R _t的估计方法 历史悠久，得到广泛开发，现在通过应用于 COVID-19 大流行而得到增强。虽然对R _t的回顾性分析提供了对流行病动态和控制策略在先前暴发中的影响的洞察力，但对R _t解释的误解在 COVID-19 大流行期间，随着对该参数的更广泛认识和近乎实时的监测以及报告的病例数据而出现。在这里，我们讨论了一些关于使用R _t 作为人口风险晴雨表的普遍误解，以及它作为有关放宽非药物干预的政策决定的“开/关”开关的相关用途。当感染计数不可靠时，根据下游数据（例如住院）计算 R _t 会加剧传播发生和事件记录之间的滞后。我们还讨论了显示 R _{t之间各种关系的分析} 不同环境下的流动性、疫苗接种覆盖率和测试-追踪-隔离干预措施。