Excel spreadsheet to estimate of real-time reproduction number from case onset data, using the Wallinga-Teunis model (Am J Epidemiol, 2004).

The model requires two sets of data (green cells in spreadsheet): the number of new onsets per day, and the distribution of the serial interval of infection. The distribution is by default assumed to be Poisson, but frequency data can be entered manually into the orange cells.

As long as under-reporting is consistent over time, the reproduction number estimates will not be biased by the reporting rate.

Wallinga, J. and Teunis, P. Different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures. Am J Epidemiol. 2004;160:509–516.