Norovirus, sometimes known as winter vomiting bug in the UK, is the most common cause of viral gastroenteritis in humans. It affects people of all ages. The virus is transmitted by fecally contaminated food or water, by person-to-person contact, and via aerosolization of vomited virus and subsequent contamination of surfaces. The virus affects around 267 million people and causes over 200,000 deaths each year; these deaths are usually in less developed countries and in the very young, elderly and immunosuppressed.