Abstract
To characterize the progression of a pandemic, a well interpretable reproduction number is introduced which is easily applicable to many different situations due to its handy analytical form. On the basis of its derivation it can be understood as a cross between a volatile instantaneous reproduction number and the more robust effective reproduction number commonly used. Starting from it, a further quantity, termed acceleration parameter, is introduced, which facilitates a more differentiated characterization of the infection dynamics. In particular, it enables the precise determination of when the limit to exponential growth is reached and exceeded. A variety of possible developments is examined, including linear and exponential growth of the infection numbers as well as sub- and super-exponential growth. It turned out useful to incorporate the incidence as a further epidemiological indicator. It is used for calculating the trace that the progression of the pandemic leaves behind on a plain spanned by itself and the acceleration parameter. This plane can be divided into a dangerous area, where the pandemic becomes uncontrollable, and a safer area that must be the target of mitigation efforts. At present, many countries and the world as a whole are mired in the dangerous area.
Microfluidic characterization of macromolecular liquid–liquid phase separation
