The within-host viral kinetics of SARS-CoV-2 infection and how they relate to a person’s infectiousness are not well understood. This limits our ability to quantify the impact of interventions on viral transmission. Here, we develop viral dynamic models of SARS-CoV-2 infection and fit them to data to estimate key within-host parameters such as the infected cell half-life and the within-host reproductive number. We then develop a model linking viral load (VL) to infectiousness and show a person’s infectiousness increases sublinearly with VL and that the logarithm of the VL in the upper respiratory tract is a better surrogate of infectiousness than the VL itself. Using data on VL and the predicted infectiousness, we further incorporated data on antigen and RT-PCR tests and compared their usefulness in detecting infection and preventing transmission. We found that RT-PCR tests perform better than antigen tests assuming equal testing frequency; however, more frequent antigen testing may perform equally well with RT-PCR tests at a lower cost but with many more false-negative tests. Overall, our models provide a quantitative framework for inferring the impact of therapeutics and vaccines that lower VL on the infectiousness of individuals and for evaluating rapid testing strategies.

SARS-CoV-2 感染的宿主内病毒动力学及其与人的传染性之间的关系尚不清楚。这限制了我们量化干预措施对病毒传播影响的能力。在这里，我们开发了 SARS-CoV-2 感染的病毒动态模型，并将其与数据进行拟合，以估计关键的宿主内参数，例如受感染的细胞半衰期和宿主内的繁殖数。然后，我们开发了一个将病毒载量 (VL) 与传染性联系起来的模型，并显示一个人的传染性随 VL 呈次线性增加，并且上呼吸道 VL 的对数比 VL 本身更能代表传染性。利用 VL 数据和预测的传染性，我们进一步整合了抗原和 RT-PCR 检测的数据，并比较了它们在检测感染和预防传播方面的有用性。我们发现，假设检测频率相同，RT-PCR 检测的效果优于抗原检测；然而，更频繁的抗原检测可能与 RT-PCR 检测同样有效，且成本更低，但假阴性检测更多。总体而言，我们的模型提供了一个定量框架，用于推断降低 VL 的治疗方法和疫苗对个体传染性的影响，并评估快速检测策略。