* Most patients to get Glaxo's H1N1 vaccine Pandemrix

* Baxter's Celvapan for those with egg allergies

* British swine flu deaths now top 100

(Adds more quotes, shots for British forces in Afghanistan)

By Kate Kelland

LONDON, Oct 15 (Reuters) - Britain, which has seen more than 100 deaths linked to the H1N1 swine flu virus, will start a nationwide vaccination programme next week, its chief medical officer said on Thursday.

The UK is the latest to begin mass immunisation ahead of a feared second wave of infections. Similar programmes are already underway in the United States, China and Australia.

A total of 415,000 doses of GlaxoSmithKline's <GSK.L> Pandemrix shot will be delivered from Oct. 21 to immunise high-risk hospital patients and front-line healthcare workers.

"The programme will be rolling from next week," medical chief Liam Donaldson told reporters.

From the week beginning Oct. 26, 4.4 million doses of Pandemrix and 49,000 doses of Baxter's <BAX.N> Celvapan will be delivered to family doctors for patients in priority groups.

David Salisbury, director of immunisation, said Britain was expecting more vaccines to come from Baxter but added: "We are much less confident of their delivery schedule than we are of GSK's" due to yield problems.

The government has previously said the first to be immunised would be about 5 million people aged over six months in current seasonal flu risk groups, all pregnant women, contacts of people with compromised immune systems, and front-line health and social care workers. In total, around 11 million people are in line for the first phase of vaccination.

All those over 10 years of age receiving Glaxo's vaccine will get a single shot, but children from six months to 9 years will receive two doses, as will everybody receiving Celvapan.

Baxter's Celvapan, which is produced by cell culture, will be mainly reserved for people with egg allergies.

Donaldson also said a further 15,000 doses of vaccine would be offered to British troops serving in Afghanistan.

Responding to concerns about giving swine flu shots to pregnant women, officials said they were confident the vaccines were safe and offered a valuable protection against a potentially dangerous disease.

"I do not want to see pregnant women dying of a preventable disease -- that's the bottom line," Donaldson said.

Health officials said that in the past week there were an estimated 27,000 new cases of H1N1 flu, up from around 18,000 in the previous week, and the total number of deaths rose past 100.

There have now been 83 deaths from swine flu in England, 15 in Scotland, four in Wales and four in Northern Ireland.

Donaldson said he was "concerned about the relatively high number of patients" who were becoming seriously ill, adding that the proportion of hospitalised patients in critical care was at its highest level in Britain since the outbreak began.

"For most of the time it's been about 12 to 13 percent, but now it's up to 20 percent -- suggesting we are seeing more serious cases," he said. "There is no sign of any change in the virus, but this is giving me some concern." (Writing by Ben Hirschler; editing by Elaine Hardcastle)

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