The statistical software R (3) was used for data cleaning (an extensive process) and exploratory analysis. The maptools package (4) was used to generate maps of the geographical disease progression. Fig. 1A provides an example time series for the cumulativeconfirmed measles cases in Harare, the capital of Zimbabwe, where all age categories have been combined. Indicated in green is the mass vaccination campaign that took place between May 24 and June 2. Fig. 1B provides an example map displaying the geographical distribution of confirmed measles cases upon extinction of the outbreak. The darker color indicates a higher attack rate (number of confirmed cases divided by total population); the darkest red area is Harare.