Every year, we experience an outbreak of the seasonal flu during the winter months. It affects around 5-15% of the population and most of the complications and deaths tend to affect the elderly population. The swine flu virus, however, typically affects the younger population, i.e. from 5 to 65 years. Most will experience a mild illness and make a full recovery. Children and young adults appear to be most susceptible to clinical infection with the highest incidence in 5-9 and 10-14 year olds, with a smaller number of cases in adults older than 50 years of age (born before 1957). The low number of cases seen in those aged over 50 is thought to be due to previous exposure in this age group to similar strains of H1N1 that circulated between 1918 and 1957. The median duration of illness is estimated at 7 days. However, people who are in the at risk group such as those with underlying medical conditions e.g. chronic respiratory disease, asthma, diabetes, chronic heart disease, chronic renal disease, chronic liver disease, morbidly obese, those who are on medication to suppress their immune system and children under the age of 5 years. Pregnant women are all at higher risk of developing complications should they catch the infection. The illness may be complicated by bronchitis, or viral or secondary bacterial pneumonia.