Mitigation and herd immunity strategy for COVID-19 is likely to fail

Wolfgang Bock; Barbara Adamik; Marek Bawiec; Viktor Bezborodov; Marcin Bodych; Jan Pablo Burgard; Thomas Goetz; Tyll Krueger; Agata Migalska; Barbara Pabjan; Tomasz Ozanski; Ewaryst Rafajlowicz; Wojciech Rafajlowicz,; Ewa Skubalska-Rafajlowicz; Sara Ryfczynska; Ewa Szczurek; Piotr Szymanski

Semi-realistic microsimulations for Germany and Poland, on the basis of our model, give strong indications that there is only a narrow feasible interval of epidemiologically relevant parameters within which a successful mitigation is possible. Social distancing measures imposed by state authorities can hardly be fine-tuned enough to hit this critical interval precisely. Furthermore, herd immunity within these intervals is at best 15% percent of the population and would hence not provide sufficient protection for a second epidemic wave. The main reason for the narrowness of the mitigation interval as well as for the low critical value R min is the household structure. Infections within the households for patients with mild progression can hardly be avoided and therefore a small number of infection links between the households can already make the epidemic overcritical. In the subcritical domain we observe a strong dependence of time till extinction on the outreproduction number R*. Reasonable extinction times are only achievable for very low values below 1/3 secondary infections outside of households. We conclude that instead, an extinction strategy implemented by quick, effective 11 . CC-BY-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.