The challenges of containing SARS-CoV-2 via test-trace-and-isolate

Abstract Without a cure, vaccine, or proven long-term immunity against SARS-CoV-2, test-trace-and-isolate (TTI) strategies present promising tool to contain its spread. For any TTI strategy, however, mitigation is challenged by pre- and asymptomatic transmission, TTI-avoiders, undetected spreaders, which strongly contribute ”hidden" infection chains. Here, we study semi-analytical model identify two tipping points between controlled uncontrolled spread: (1) the behavior-driven reproduction number $${R}_{t}^{H}$$ R t H of hidden chains becomes too large be compensated capabilities, (2) new infections exceeds tracing capacity. Both trigger self-accelerating We investigate how these depend on challenges like limited cooperation, missing contacts, imperfect isolation. Our results suggest that alone insufficient an otherwise unhindered spread implying complementary measures social distancing improved hygiene remain necessary.