Influenza, or ‘flu’, is a highly contagious acute viral infection that affects people of all ages. It typically starts suddenly with fever, chills, headache, aching muscles, general prostration and a cough or other respiratory symptoms. While most people recover without complications in 1-2 weeks, flu can cause serious illness and death, especially in the very young and the elderly. Flu epidemics occur mainly in the winter months and can result in widespread disruption to healthcare and other services. A vaccine is produced every year based on the strains of virus expected to be circulating