ABSTRACT This proposal is to enhance the New Vaccine Surveillance Network (NVSN) site in Rochester, NY, which has for 10 years been focused on prospective, population-based surveillance for acute gastroenteritis (AGE) caused by rotavirus, norovirus, and other viral pathogens, and for the past year, population-based surveillance for acute respiratory infections. We propose to continue and extend surveillance for ARI with a focus on influenza, respiratory syncytial virus (RSV), enterovirus-D68 (EV-D68), and other vaccine- preventable or potentially vaccine-preventable viruses, in order to both measure influenza vaccine effectiveness (VE) in preventing laboratory-confirmed influenza infections among hospitalized children <18 years of age, and to assess the inpatient burden of viral pathogens associated with ARIs, particularly influenza, RSV and EV-D68. We also will continue the AGE surveillance to allow for similar determinations of AGE burden and rotavirus vaccine efficacy among children hospitalized or visiting the emergency departments. The over-arching goal of the NVSN is to inform the nation about the burden of vaccine-preventable diseases (VPDs), and the impact of new vaccines and vaccine policies. Our Rochester NVSN site (a founding NVSN member), has been a leader in shaping all aspects of the NVSN, including population-based surveillance for new or upcoming vaccines, vaccine effectiveness (VE) studies, refinement of diagnostic laboratory methods, health services and epidemiologic studies, and dissemination of findings. We have the infrastructure and comprehensive expertise to begin all activities on day 1 of the funding period. Our NVSN site has: experienced personnel who have led and published many past NVSN influenza VE, surveillance, and molecular diagnostic laboratory studies; accurate laboratory and surveillance techniques consistent with CDC procedures; and outstanding epidemiologic and health services research capabilities. We have full access to all hospital and ED databases to complement surveillance activities. Our catchment area, the Monroe County NY/Rochester Metropolitan Statistical Area, has a total population of >1,000,000; >95% of ARI admissions for Monroe County resident children <18 years of age occur at our two NVSN hospitals, with nearly 1,000 hospitalizations for ARIs per year. Thus, we have a “captured population” precisely suited for the NVSN population-based surveillance projects. This proposal will provide critical information to develop sound polices consistent with national goals to preventing VPD in children.