Basic prediction methodology for covid-19: estimation and sensitivity considerations

Tom Britton

We now describe how to derive an expression, or rather a range of r E -values, to which the preventive measures will change the exponential growth to. We start by deriving an expression using relation (1) . First of all, the growth rate r prior to preventive measures, is estimated from the cumulative reported deaths as described above. Suppose further that an estimate of R 0 is available (from contact tracing, prior knowledge, or other method). Using the estimates of r and R 0 we obtain an estimate g 1 of g using (1). If preventive measures are introduced, then the reproduction number changes from R 0 to R E = (1 − ρ)R 0 . The mean generation time remains unchanged (this might not hold if enforced contact tracing is included among the introduced preventive measures). As a consequence, the new exponential growth rate satisfies