Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077, Göttingen, Germany.
Centre for Biotechnology and Bioengineering, Universidad de Chile, Beauchef 851, 8370456, Santiago, Chile.
Nat Commun. 2021 Jan 15;12(1):378. doi: 10.1038/s41467-020-20699-8.
Without a cure, vaccine, or proven long-term immunity against SARS-CoV-2, test-trace-and-isolate (TTI) strategies present a promising tool to contain its spread. For any TTI strategy, however, mitigation is challenged by pre- and asymptomatic transmission, TTI-avoiders, and undetected spreaders, which strongly contribute to "hidden" infection chains. Here, we study a semi-analytical model and identify two tipping points between controlled and uncontrolled spread: (1) the behavior-driven reproduction number [Formula: see text] of the hidden chains becomes too large to be compensated by the TTI capabilities, and (2) the number of new infections exceeds the tracing capacity. Both trigger a self-accelerating spread. We investigate how these tipping points depend on challenges like limited cooperation, missing contacts, and imperfect isolation. Our results suggest that TTI alone is insufficient to contain an otherwise unhindered spread of SARS-CoV-2, implying that complementary measures like social distancing and improved hygiene remain necessary.
在没有治愈方法、疫苗或针对 SARS-CoV-2 的长期有效免疫力的情况下，检测-追踪-隔离（TTI）策略是控制其传播的有前途的工具。然而，对于任何 TTI 策略，减轻由潜伏期和无症状传播、TTI 回避者和未被发现的传播者所带来的挑战都极具难度，这些因素大大增加了“隐匿”感染链的可能性。在这里，我们研究了一个半分析模型，并确定了两种控制和不受控制的传播之间的转折点：（1）隐匿传播链的行为驱动繁殖数[公式：见文本]变得太大，无法通过 TTI 能力来弥补；（2）新感染的数量超过了追踪能力。这两种情况都会引发自我加速传播。我们研究了这些转折点如何取决于有限的合作、缺失的接触和不完善的隔离等挑战。我们的研究结果表明，TTI 本身不足以控制 SARS-CoV-2 的不受阻碍的传播，这意味着仍然需要采取社交距离和改善卫生等补充措施。
