Estimates of the attack rate for Influenza vary greatly. In [19] the authors report an attack rate of 68% among servicemen during an H1N1 outbreak in Finland during the winter of 1977-78. Among the 1575 surveyed in La Gloria an attack rate of 39% (615/1575) was observed. Finally, a recent report in Peru [20] indicates that 33% of cases were asymptomatic, meaning that the attack rate in La Gloria could actually be as high as 58% if we Figure 2 Simulation results for the estimate of the mean of the serial interval. The first boxplot in each frame shows results when all the data is used. Each couplet thereafter shows estimates when missingness is correctly accounted for on the left and on the right, when missingness is ignored in estimation. The numbers on the × axis denote the missingness scheme applied to the data(see text of manuscript for a detailed description). The horizontal line indicates the true value of the parameter. For several of the gamma distribution scenarios the actual estimates are extremely large and thus the value of the median is included on the plot where necessary.