Swine flu, officially known as Influenza A (H1N1) by the World Health Organisation, is more than ever present on the news agenda. In June, the WHO raised the alert level to scale 6, making it the first official pandemic of the 21st century.

The virus, which first appeared in Mexico, has spread across the world. According to the WHO's latest figures, it has hit 177 countries and caused 2,837 deaths.

The organisation claims that if nothing is done to stop the virus spreading, 2 billion people could end up contracting it. That's approximately one third of the world's population.

So far mainland France has seen few cases of the illness, but the government remains on high alert. Each year between 3 and 5 million French people catch seasonal flu. With swine flu, that figure could rise to as high as 20 million.
 

Governments around the world have been working on battle plans to curb the virus's spread. But in most places, vaccines against swine flu will not be available until October. Doubts about the vaccine remain, including who should be treated in priority.