Improving the reproduction number calculation by treating for daily variations of SARS-CoV-2 cases

Drewes, H.; Flaeschner, G.; Moeller, P.

The Covid-19 pandemic impacted the human life all over the globe, starting in the year of its emergence, 2019, and in the following years. A epidemiological key indicator that gained particular recognition in politics and decision making is the time-dependent reproduction number R_t, which is commonly calculated by institutions responsible for disease control following a method presented by Cori et. al. Here, we propose an improved as well as an alternative method, which makes the calculation more stable against oscillations arising from daily variations in testing. Both methods can be used without great statistical knowledge or effort. The methods provide a smoother result without increasing the time-lag, and provides an advantage particularly in the timeframe of weeks, which might serve as a better ground for forecasts and the raising of alarms.