What is pandemic (H1N1) 2009 influenza?

Pandemic (H1N1) 2009 influenza (previously called Human Swine Flu) is a new strain of flu that hasn’t affected the current world population before. It’s affecting people in many countries around the world and seems to be spreading fast.

Because it’s new, people have no immunity to it and there is no vaccine. It will take some months for a vaccine to be developed, and longer for it to be available in large amounts.

The virus causes illness in all age groups, but seems to affect young people under the age of 30 most, and is spreading fast particularly among people aged 10 to 45 years.

What sort of illness does the virus cause?

The virus causes disease that ranges from very mild to severe, and can result in death. Most people who get sick have the milder disease and get better within a week without antiviral treatment or medical care.

More than half of the people hospitalized with the illness have underlying health conditions or weak immune systems. Some are previously healthy, young people.

Key symptoms are fever, with cough and/or sore throat. Other common symptoms include headache, a general feeling of being unwell, fatigue, muscular aches, joint pains, rigors or chills, diarrhoea and vomiting.

Who is most at risk of serious illness?

Certain groups of people are more at risk of severe illness from H1N1 Influenza. Find out more about who is at risk from influenza in 2009.

Frequently asked questions

A series of frequently asked questions about H1N1 Influenza are available to read and download, and are regularly updated.