San Francisco Sudden Unexpected Infant Death (SUID) and Sudden Death in the Young (SDY) Case Registry: SUID Component A and SDY Component B - Sudden Unexpected Infant Death (SUID) and Sudden Death in the Young (SDY) are critical public health issues with devastating impacts on families, care providers, and the community. Historically, causes of death in young populations have been poorly studied and classified, leading to inaccurate incidence data from which public health interventions can be applied. Furthermore, the global COVID-19 pandemic has magnified healthcare disparities, revealing a dire need for continued surveillance of SUID/SDY in vulnerable communities. The principal investigator (PI) of this application, Zian Tseng, has established the necessary infrastructure and multidisciplinary collaborations, including cardiac electrophysiology, pediatric cardiology, forensic pathology, neurology, epileptology, genetic counseling, and child death review team leaders, for a successful extension of our involvement with the SUID and SDY Case Registry. Our NHLBI-funded, ongoing San Francisco POST SCD (POstmortem Systematic InvesTigation of Sudden Cardiac Death) Study established a highly successful collaboration with the San Francisco Medical Examiner to fully investigate and autopsy all adult sudden deaths since 2011. As one of the original CDC SUID and SDY Case Registry grantees in 2015, we were able to leverage this collaboration to accurately describe the incidence and epidemiology of SUID/SDY in San Francisco. This allowed us to identify disparities, promote equitable investigations, and guide SUID/SDY prevention measures. We propose the extension of these activities and collaborations to continue to fully investigate all incident SUID/SDY in San Francisco with complete capture of data, including autopsy/pathology reports, death certificates, medical records, paramedic runsheets, death scene and police investigation, biospecimen collection, genetic testing. Every SUID/SDY case will be reviewed in a timely manner by the Child Death Review (CDR) Team and Clinical Advanced Review Team and categorized according to the CDC’s algorithm. On cases where we successfully engage family members to consent for access to autopsy tissue specimens for molecular and genetic analyses, we will provide clinical screening recommendations and genetic counseling to at-risk families. Outcomes include: (1) Maintain completeness, timeliness, and quality of SUID and SDY surveillance data, particularly with respect to social determinants of health (SDOH), for program improvement and public health purposes. (2) Increase the dissemination of data briefs and other products to inform internal and external stakeholders, including but not limited to death investigators, safe-sleep organizations, and public health officials. (3) Increase in the number of implemented policies and practices to standardize and reduce inequity in investigation practices, including review of medical records, scene investigation and autopsy protocols. Our team is committed to supporting other CDC Registry sites and are available for consultations on cardiac pathology and evaluation of cardiac devices. As a clinical and research institution with a unique perspective on SDY/SUID cases, we will contribute our insights towards the nationwide registry beyond the scope of our local cases.