The main idea in this paper is that the age associated with reported measles cases can be used to estimate the number of undetected measles infections. Somewhat surprisingly, even with age only to the nearest year, estimates of underreporting can be generated at the much faster, 2 week time-scale associated with measles transmission. I describe this idea by focusing on the well-studied, 60 city United Kingdom data set, which covers the transition to universal healthcare in 1948, and is, as a result, an interesting case study in infectious disease surveillance. Finally, at the end of the paper, I comment briefly on how the approach can be modified for application to modern contexts.
