A new method for calculating the Effective Reproduction Number

We have finalised a technical report that provides the full mathematical details of a new method for calculating the Effective Reproduction Number for COVID-19. The technical report is here.

The new process which we have called "SIR+B" combines a deterministic SIR formula for calculating the Effective Reproduction Number from positive test data and a statistical bootstrapping method for generating confidence intervals.

The process has been used to calculate the Effective Reproduction Number for several countries in this blog post.

The process has the following desirable outcomes.

• it is fast, taking about 0.1 seconds per country analysed, when coded in Python on a standard desktop machine

• it is based directly on the epidemiological SIR model, giving an analytic formula for the Effective Reproduction Number

• it involves many fewer assumptions than other methods such as EpiEstim

• the calculation of the Effective Reproduction Number depends on only two parameters, gamma - the recovery parameter, and c - the testing parameter

• it is relatively insensitive to those parameters