Fraenkel CJ, et al. - Researchers here investigated risk factors for norovirus (NoV) outbreaks in hospital settings. Outbreak was independently associated with the number of patients sharing room with the NoV case, vomiting, age > 80 years, comorbidity and onset of symptoms after admission to the ward. Infection with genotype GII.4 was found to have a strong correlation with the outbreak. This, in part, might be explained by an enhanced ability to induce vomiting. Recognition of these factors could help in direct and prioritise infection control actions based on the outbreak risk.