The National Respiratory and Enteric Virus Surveillance System (NREVSS) is a laboratory-based system that monitors temporal and geographic circulation patterns (patterns occurring in time and place) of respiratory syncytial virus (RSV), human parainfluenza viruses (HPIV), human metapneumovirus (HMPV), respiratory adenoviruses, human coronavirus, rotavirus, and norovirus. In this surveillance system, participating U.S. laboratories voluntarily report weekly to CDC the total number of weekly aggregate tests performed to detect these viruses and the weekly aggregate positive tests. They also report the specimen type, location and week of collection. NREVSS allows for timely analysis of data to monitor viral seasons and circulation patterns.