DESCRIPTION (provided by applicant): The overall goal of this project is to establish a population-based surveillance of the effectiveness of rotavirus vaccine by assessing the prevalence and incidence of acute gastroenteritis (AGE) disease in young children, especially due to rotavirus. The addition of effective new vaccines (e.g. pneumococcal conjugate and rotavirus vaccines) to the current childhood immunization schedule represents a great opportunity for improvement of the public health. As new vaccines are introduced, a thorough and complete public health strategy must be introduced to ensure post-marketing safety and effectiveness. In addition to new vaccines requiring a surveillance network, older vaccines that are being introduced into new populations also require a similar approach, such as influenza vaccine now being recommended to include all children aged 6 months-18 years. Vanderbilt Investigators have a 10-year track record of population-based approach to viral and AGE surveillance in Davidson County. We are confident that the team has maintained excellent surveillance in the past and will be able to do so as part of this proposal.