Modeling Exit Strategies from COVID-19 Lockdown with a Focus on Antibody Tests

Reinhard German; Anatoli Djanatliev; Lisa Maile; Peter Bazan; Holger Hackstein

The contribution of this paper is to investigate for a country like Germany combinations of measures in order to get an effective exit strategy and to meet the important goals mentioned above. We will thus investigate the following scenarios: disease dynamics if no lockdown would have been imposed, an exit of the lockdown without successive measures, hygienic constraints imposed after lockdown, and repetitive and adaptive but short-term social contact restrictions. Isolation of infectious people, seasonality of contagiousness, and immunity of a large fraction of the population is also considered. Antibody tests are used in order to let return people with assumed immunity to public life without contact reductions. Since such tests are a scarce resource it will not be possible to test all people systematically. Therefore it will be necessary to develop strategies such that a positive effect can be achieved. One approach is to give people from risk groups or from system relevant sectors preference, such as health personnel. A second approach is to follow infection chains and identify people who might have been infected but were asymptomatic (digital contact tracing could help here). If that is possible, these people will be also tested with preference leading to a higher fraction of people able to reenter public life. We will first examine these strategies with an extended SD model in order to get main hints. We will then show an ABS model for a prototypical region with different classes of people. The ABS model will be used in followup work to check whether properties of testing are sufficient or must be improved. In the SD model all effects are aggregated in rates for the complete population, whereas in the ABS individual contacts between people in families, at work, in hospitals, and in leisure are modeled. Thus the ABS allows to draw conclusions also for the availability of personnel in hospitals and in companies. This also allows for planning over the time during and after lockdown. Both models have been realized with the simulation framework AnyLogic 2 .