Children bear a considerable proportion of the impact of epidemics of influenza and measles and are a driving force in community-wide epidemics. This thesis considers this impact and the benefits of existing vaccination programmes. First, we estimated the impact of seasonal influenza outbreaks in primary schools. To estimate the health-related impact we started by conducting a review of the literature to determine the methods used to estimate health utilities in children and adolescents, establishing that a wide variety of systems have been used without clear guidance on an optimal method. Mean absence from school was 3.8 days (95% CI: 3.0-4.8) and 3.7 days (95% CI: 2.7-4.8) off work for caregivers. The mean loss in HRQoL was 2.1 QALDs (95% CI: 1.5-2.7). Next, we modelled the childhood influenza vaccination programme at a national- and communitylevel, exploring the impact of heterogeneous coverage. Nationally, a vaccination programme that focuses on primary school vaccination supplemented with fewer vaccinations in secondary schools is optimal from the perspective of the healthcare provider, but heterogeneous uptake within targeted populations consistently resulted in a larger total burden of disease at the community level, emphasising the importance of adherence to school-based vaccination policies. Two studies of the measles outbreaks in England between 2012 and 2013 were conducted to further the understanding of the impact of measles infection. Significant work/school absence was reported by individuals with infection and their caregivers. Infection was associated with a mean loss of 6.9 QALDs (95% CI: 5.8-8.0). The total economic cost of the outbreak was £4.4m in Merseyside alone, compared to a total cost of £182,909 over the previous five years to achieve herd immunity through the MMR vaccination programme. The findings demonstrate the importance of adherence to preventative vaccination programmes to reduce the potential for outbreaks of influenza and measles.