Adaptive cyclic exit strategies from lockdown to suppress COVID-19 and allow economic activity

Omer Karin; Yinon M. Bar-On; Tomer Milo; Itay Katzir; Avi Mayo; Yael Korem; Boaz Dudovich; Amos J. Zehavi; Nadav Davidovich; Ron Milo; Uri Alon

Each region shows the maximal number of work days in a 14-day cycle that provide decline of the epidemic. Simulation used a SEIR-Erlang deterministic model with mean latent period of 3 days and infectious periods of 4 days. Results are robust to uncertainty in model parameters (Fig S2) . An important consideration is that the cyclic strategy is adaptive, and can be tuned when conditions change and the effects of the approach are monitored. For example, weather conditions may affect R ( 5 ) , as well as advances in regional monitoring and case tracing. If one detects, for example, that a 4:10 strategy leads to an increasing trend in cases, one can shift to a cycle with fewer work days. Conversely, if a strong decreasing trend is observed, one can shift to more work days and gain economic benefit (Fig 5) . A conservative approach can exit lockdown with 1 day of work, build up to two days, and so on. Measures will be required during the work days to ensure that people do not excessively compensate for the lockdown periods by having so many more social connections that R is significantly increased. This may include sound epidemiological measures such as the continuation of banning large social events and clear communication campaigns by the health authorities to enhance adherence to hygiene and physical distancing. Shared work spaces can be disinfected to reduce future infection through surfaces. Extensive rapid testing and contact tracing should be developed and extended in parallel ( 12 ) .