Background: Vaccinating children against influenza virus may reduce infections in immunised children and household contacts, thereby reducing the household-based cost associated with respiratory illnesses. Objective: To evaluate the impact of influenza virus vaccination of daycare children on...

Standard methods for the analysis of cluster-correlated count data fail to yield valid inferences when the study is finely stratified and the interest is in assessing the intracluster correlation structure. We present an approach, based upon exactly adjusting an estimating function for the bias...