10:22 03 July 2009
Last year, there were fears that the global swine flu pandemic could claim 65,000 lives across Britain. Official figures show 457 people died, but now there are signs of a new wave of the virus spreading across the country again.
Seven people have died from swine flu in Greater Manchester alone this winter, with the nationwide death total currently standing at 20. Two hundred people are also said to be in intensive care fighting for their lives.
If you are worried, this comprehensive guide from the BBC has plenty of answers:
What is swine flu?
Swine flu is a respiratory disease, caused by a strain of the influenza type A virus known as H1N1.
H1N1 is the same strain which causes seasonal outbreaks of flu in humans on a regular basis.
But this latest version of H1N1 is different: it contains genetic material that is typically found in strains of the virus that affect humans, birds and swine.
Although the strain may have originated in pigs, it is now a wholly human disease.
It can be spread from person to person by coughing and sneezing.
Symptoms of swine flu in humans appear to be similar to those produced by standard, seasonal flu.
These include fever, cough, sore throat, body aches, chills and fatigue.
What should I do if I think I have it?
Anyone with flu-like symptoms who might have been in contact with the swine virus should seek medical advice.
They are being advised to phone NHS Direct - NHS 24 in Scotland - or their GP.
If swine flu is suspected, a voucher for anti-flu drugs will be given.
The infected person would then be expected to arrange for a friend or family member to pick up the anti-viral treatment for them from a collection point, most probably a pharmacy.
In the initial phase of the outbreak, lab testing was done to diagnose the flu but this is no longer happening routinely.
As yet there is no vaccine, but manufacturers are trying to develop one. Good progress is being made and the first doses may be available in the UK by August.
What measures can I take to prevent infection?
Avoid close contact with people who appear unwell and who have fever and cough.
General infection control practices and good hygiene can help to reduce transmission of all viruses, including the human swine influenza. This includes covering your nose and mouth when coughing or sneezing, using a tissue when possible and disposing of it promptly.
It is also important to wash your hands frequently with soap and water to reduce the spread of the virus from your hands to face or to other people and cleaning hard surfaces like door handles frequently using a normal cleaning product.
In Mexico masks have been handed out to the general public, but experts are sceptical about how useful this is.
What does a pandemic mean?
In many ways, the flu outbreak becoming a pandemic is just a label. It means its is spreading rapidly from human-to-human in two World Health Organization regions.
The move to the pandemic stage - the sixth and final stage of the rating system - makes no difference to individual government flu plans.
What matters most for countries is what is happening inside their own borders.
In the UK, the approach being taken is to contain the disease. This involves isolating cases, giving them drugs and tracing their contacts and giving them drugs in a bid to put a wall around the virus.
While it is gradually spreading, the tactic is still working to some degree and the UK government says it will continue doing this for the immediate future.
How dangerous is it?
So far, most cases of swine flu around the world appear to be mild, albeit with diarrhoea more common than it is with seasonal flu.
The WHO says that many people who develop symptoms of infection have not needed drugs to make a full recovery.
Flu expert Professor Peter Openshaw, of Imperial College London, says about one in every three people who become infected will not realise they have had swine flu because they will have had no or only very few symptoms.
"About about 98% of people who get infected will recover fully without any hospital treatment so I think the public needs to be reassured."
The real fear is that the strain will mutate and become more virulent which would pose a greater threat.
However, it is still worth remembering that seasonal flu often poses a serious threat to public health - each year it kills 250,000 - 500,000 around the world.
Can it be treated?
Two drugs commonly used to treat flu, Tamiflu and Relenza, are effective at treating infection.
However, the drugs must be administered at an early stage to be effective.
Use of these drugs may also make it less likely that infected people will pass the virus on to others.
The UK government already has a stockpile of Tamiflu, ordered as a precaution against a pandemic.
However, there is concern that if too many people start taking anti-virals as a precaution, it could raise the risk of the virus developing resistance, reducing the drugs' effectiveness.
Where can I get further advice?
Further information and advice on swine flu can be found at websites of leading health and research organisations around the world. The World Health Organisation gives background information on the virus.
The UK's government services website is carrying regularly updated health and travel information. The Health Protection Agency advises the public about what to do if returning from an affected area. NHS Choices outlines how swine flu is different from other flu.
The US government's Centre for Disease Control is counting the number of cases in the US.
Source: BBC