Before revision:  Two simple rules for the optimal control of the effective reproduction number are presented, see Eqs. (13)-(14), which ensure a stable route out of the initial lockdown. The rules are directly applicable in practice, as they only depend on a precise knowledge of the cumulative number of cases and a reliable estimate of the effective reproduction number. The obtained results could serve as a guideline for the implementation and gradual relaxation of non-pharmaceutical intervention measures also in other scenarios, e.g., when the development of a vaccine is expected soon .
After revision:  Two simple rules for the optimal control of the effective reproduction number reveals, however, that the obtained solution is in fact a tightrope walk close to the stability boundary of the system, where socio-economic costs and the risk of a new outbreak must be constantly balanced against one another .