In the past three years, the incidence of infection with the H5N1 variant of avian flu has increased in humans in southeast Asia during periods corresponding to winter and spring in the northern hemisphere.1 More cases of H5N1 infection in humans increase the chances that the virus will adapt towards efficient transmission between humans and therefore of a flu pandemic.

The United Kingdom is well advanced in its preparations for a flu pandemic.2 The British Infection Society, British Thoracic Society, Health Protection Agency, and Department of Health have recently developed and published provisional guidelines on the clinical management of pandemic flu.3 These guidelines cover the clinical management of children and adults with flu during a pandemic.

In interpandemic years when influenza is circulating in the community, presentation with acute fever and new (or in chronic lung disease, worsening) cough is highly predictive of flu in adults.4 In a pandemic, key predictive features may change as a result of altered thresholds …