Understanding influenza: Summary
- Influenza or 'flu' is a highly infectious viral illness, spreading easily from person to person either through the air or through hand/face contact.
- Annual outbreaks of 'ordinary' flu arise as a result of minor genetic changes in the flu viruses known as antigenic drift which produce different strains each year.
- The more a flu strain differs from previously circulating strains, the less immunity a population will have to it.
- 'Ordinary' flu epidemics kill between 500,000 and 1 million people worldwide every year; in the UK, they affect up to 10-15% of the population each year and cause around 12,000 deaths.
- A pandemic flu virus is a novel flu virus to which the population has very little or no immunity.
- Pandemic flu emerges as a result of major genetic changes in the flu virus known as antigenic shift and occurs roughly every 30 years.
- Pandemic flu is generally associated with much higher rates of illness than 'ordinary' flu, affecting a quarter of the population or greater, and more deaths.
- The worst flu pandemic last century killed around 40 million people worldwide and around 250,000 people in the UK alone.
- For more information about flu and pandemic flu visit:
