SARS-Cov-2 proliferation: an analytical aggregate-level model

Pitschel, T.

An intuitive mathematical model describing the virus proliferation is presented and its parameters estimated from time series of observed reported CoViD-19 cases in Germany. The model replicates the main essential characteristics of the proliferation in a stylized form, and thus can support the systematic reasoning about interventional measures (or their lifting) that were discussed during summer and which currently become relevant again in some countries. The model differs in form from elementary SIR models, but is contained in the general Kermack-McKendrick (1927) model. It is maintained that (compared to elementary SIR models) the model is more faithfully representing real proliferation at the instantaneous level, leading to overall more plausible association of model parameters to physical transmission and recovery parameters. The main policy- oriented results are that (1) mitigation measures imposed in March 2020 in Germany were absolutely necessary to avoid health care resource exhaustion, (2) fast response is key to containment in case of renewed outbreaks. A model generalization aiming to better represent the true infectiousness profile is stated.