The FSA has conducted a risk assessment to assess the public health risk of raw oysters with norovirus RNA levels in order to provide guidance for managing norovirus outbreaks. Norovirus is a common virus that can contaminate food and oysters are a significant source of norovirus due to their consumption raw. The risk of illness from norovirus varies depending on the levels of the virus in oyster batches, with potential human wastewater contamination and outbreak links increasing the risk.