Pregnant women are among the highest priorities, says Sir Liam Donaldson
The swine flu vaccination programme will get under way in the UK next week, the government has said.
Patients in hospital deemed at risk of the infection - including pregnant women and people with health problems - will get the jab from 21 October.
GPs will start calling patients in the week after until 13 million people in the priority groups are vaccinated.
Meanwhile, front-line troops in Afghanistan will also be offered jabs, the Ministry of Defence said.
The troops and staff supporting operations in Afghanistan - totalling 15,000 people - will be vaccinated immediately after the programme to protect those most at risk in Britain.
The Ministry of Defence said: "Recognising the uniquely challenging task facing our troops in Afghanistan, front-line troops will be offered the jab to protect against a major outbreak of swine flu and maintain the numbers of troops available to commanders."
The announcement on the vaccination programme came as the number of deaths from the H1N1 virus hit 106 following another rise in cases.
But the rate of increase is still short of the doubling that would represent a surge in cases.
Last week chief medical officer Sir Liam Donaldson said the slow-burning nature of the second peak now being seen in the UK may be a "lucky break" as it was buying time for the roll-out of the vaccination programme.
1. Individuals aged six months to 65 years with underlying health problems and the immuno-supressed, which includes chemotherapy patients
2. Pregnant women
3. Household contacts of people with compromised immune systems
He has now confirmed that those immunisations will start next week and he urged all those identified in the priority groups to agree to have the jab.
There has been some concern about the situation regarding pregnant women as they have not been part of the clinical trial process that has tested the two jabs being used in the UK.
But experts have pointed out that a wealth of data exists on the use of seasonal flu vaccines on pregnant women - they are routinely included in the US programme, while those with health problems get the jab in the UK.
Sir Liam said it was important for pregnant women to be immunised as they have a particularly high risk of complications from swine flu - two pregnant women have died in the past week alone, including a 17-year-old from Scotland.
"The sensible approach to reducing risk is to get the vaccine. It will save lives."
But Sir Liam said he was concerned about the postal strike as GPs send out letters to invite patients for vaccination.
Troops serving in Afghanistan will also be getting the vaccine, the government has announced.
A decision has yet to be taken over whether the rest of the population will be immunised, although the government has ordered enough vaccine for the whole population.
Sir Liam said while he was encouraged by the relatively slow rise in the new infections, he was worried about the increasing number of complications being seen.
The number of deaths has jumped by 16 in the past week and a fifth of the 300-plus people in hospital are in critical care - the highest rate since the pandemic began.
Hospitals - Vaccination of at-risk patients and frontline health workers to start on 21 October and expected to take between two to three days
GPs - Will start inviting patients to come and get the jab from 26 October, could take more than a month to get everyone in the priority groups vaccinated
Others - Mental health trusts will also receive jabs from 26 October, while local health managers will coordinate the immunisation of health and social care staff working in the community
Shadow health secretary Andrew Lansley added: "This is an indication that we should not regard swine flu as always moderate in its effects. It also reinforces the case for vaccination among those people most at risk."
In total, there were 27,000 new cases in England during the past week, compared with 18,000 the week before.
Meanwhile, in Scotland, 12,500 people were thought to have contracted swine flu - up from 6,800.
Rises are also being seen in Northern Ireland and Wales.
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