PROJECT SUMMARY ABSTRACT- MANDATORY CORE The purpose for Mandatory Core Component A is to support an Enhanced Surveillance Network of US pediatric institutions to develop and implement standard research protocols to conduct prospective active population-based surveillance in defined inpatient and emergency department (ED) settings for a) acute gastroenteritis (AGE) due to norovirus, rotavirus and other enteric pathogens, b) acute respiratory infection (ARI) due to respiratory viruses including influenza, RSV, parainfluenza viruses, human metapneumovirus, rhinoviruses, enteroviruses (including EV-D68), adenoviruses, coronaviruses (including SARS-CoV-2) and other respiratory viruses, c) and healthy controls (HC) and d) Acute Flaccid Myelitis (AFM) syndrome among pediatric patients seeking healthcare at these pediatric medical institutions. The results from this program will be used to inform vaccine recommendations and assess the public health impact of the US rotavirus, influenza and SARS-CoV-2 vaccination programs and provide epidemiologic data for other infectious diseases with therapeutics and vaccines in development. There are two objectives for Mandatory Core Component A:: For Objective 1 we will conduct population-based active surveillance for respiratory and enteric viral pathogens in pediatric inpatient and ED settings and enroll asymptomatic healthy controls in Hamilton Co. children <18 years of age. Through our already established ARI, AGE and HC Surveillance Platforms we will 1) perform active surveillance to determine the etiology and burden of inpatient and ED acute viral enteric and respiratory diseases in our defined population, 2) characterize the clinical and epidemiologic factors of infections including asymptomatic children and 3) evaluate VE and impact of vaccines and other interventions available or projected to become available during the study agreement period for rotavirus and influenza vaccines using a test- negative design and for RSV and SARS-CoV-2, when available and recommended for children and adolescents. For Objective 2 we will conduct surveillance activities for acute flaccid myelitis (AFM in hospitalized children <18 years of age). Through our already established AFM Surveillance Platform, we will 1) define baseline rates of AFM in our pediatric institution through active case finding in collaboration with our Neurology and Neuroradiology Co-Investigators using the CDC's case definition for patients meeting the clinical criterion for AFM and a spinal MRI showing at least some gray matter involvement by conducting active surveillance and establishing incident rates for AFM among hospitalized children within our catchment area, 2) compare rates of AFM to rates of circulating respiratory and enteric pathogens at our site from our population- based active surveillance program and 3) characterize the clinical spectrum of pediatric AFM and compare with the clinical spectrum seen with other similar neurologic conditions.