We first consider the case where the serial interval (the p j ) is well known and specified, perhaps from contact tracing data or historical information. Then the MLE for R 0 in the complete data case is given bŷ which is comparable to the branching process estimator described by [2] , as illustrated in [5] . If p j is incorrectly specified we know that the estimates of R 0 are impacted [5] . Our interest here is the study of the impact of missingness therefore we assume that p j is correctly specified so as to avoid confounding the effect of these two issues when estimating R 0 . In the case where data is incorrectly reported, the estimator for R 0 obtained from [2] is 