May Day celebrations in Mexico have been called off because of the influenza crisis. The country’s President has urged people to stay home for the long weekend and for businesses to close.After protest from some governments, the World Health Organisation has renamed the virus A(H1N1), the scientific name, even though it has become widely known as Swine Flu. It is actually a mix of swine, avian and human viruses, and flu epidemics are usually named after the countries in which they first emerge. The number of officially confirmed cases is 331 in 11 countries. There has been a huge increase in demand for flu vaccinations in the countries affected, and governments are stocking up on anti-viral drugs. Almost all the infections outside of Mexico have been mild and only a handful of patients have required hospital treatment. The WHO says its flu alert level remains at one step below a full pandemic.