Medical centres in the UK have begun distributing a vaccine to guard against the 2009 H1N1 (swine flu) pandemic, with healthcare workers and special risk patients heading the queue.
The vaccine, which will be available at GP surgeries as of Monday 26 October, will be handed out first to around two million frontline health and social care workers.
Other risk groups identified by the health services have been prioritised in the following order:
People between the ages of six months and 65 with underlying health problems and damaged immune systems (expected to be around 5 million people).
All pregnant women (about 0.5 million people).
People who come into regular contact with patients with compromised immune systems, such as cancer sufferers (about 0.5 million people).
People aged 65 and over with health problems.
UK Health Secretary Andy Burnham said that all those in the risk groups should be offered the swine flu vaccine.
"It is also being offered to frontline health and social care workers to ensure the NHS is staffed should it come under pressure this winter," Burnham said.
As well as special risk patients and healthcare workers the government has promised that the Pandemrix vaccine, produced by GlaxoSmithKline, will be offered to the vast majority of people.
Chief medical officer Sir Liam Donaldson said that it is important for frontline health and social care workers to have the vaccine.
"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," Donaldson said.