Influenza is an acute, viral respiratory infection. Fever, chills, headache, aches and pains throughout the body, sore throat which may lead to bronchitis or pneumonia. Vomiting and diarrhoea may also occur. Many deaths have been attributed to influenza. A pandemic is a world wide spread of infection occurring in many countries simultaneously. Flu pandemics occur approximately every thirty years. Flu pandemics occur because a new strain of the virus emerges for which people have no immunity and there are no vaccines available.