A UK-wide programme of swine flu vaccinations is finally underway today as the government aims to combat the spread of the virus.
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Just over 100 people in the UK have so far died from swine flu and around 500,000 have been infected.
First to benefit from the vaccination will be the "priority group", that being seriously ill hospital patients and the staff that care for them.
But from next week GPs will begin inviting those with existing health problems, damaged immune systems and pregnant women for their jabs.
While the government has not yet decided whether the whole of the population will be immunised, enough doses have been ordered for such a programme.
Though the spread of the virus peaked during the summer months, recent weeks have seen another rise in the number of cases.
Sir Liam Donaldon, the government's chief medical officer, said: "This is the first pandemic for which we have had vaccine to protect people. I urge everyone in the priority groups to have the vaccine.
There is a worry that GPs invitation letters may be delayed by the postal strike, but Sir Liam insisted: "We are working very hard to try and get round that."
Two vaccines are set to be used – one made by GlaxoSmithLine and the other by Baxter.
Most patients will require only one dose of the vaccine, but children and those receiving the Baxter manufactured version will need two doses, three weeks apart.
Despite the daunting scale of the programme, doctors are ready and able to immunise the priority groups, though many have had to employ extra staff.
Professor Steve Field, president of the Royal College of GPs, said: "We have been planning for this for a while and everything is in place. We will be contacting patients in the coming weeks and they should wait for that."
The programme is likely to take at least two months to complete.