An estimated 4 million people in England who are at risk of severe complications or death if they contract seasonal flu remain unvaccinated this year, government health officials said yesterday.

The officials said there was "extreme difficulty" in getting the importance of immunisation across to those most at risk, with the news coming as the Department of Health revealed that 112 people across the UK had died from flu-related illness since September, with the highest number in the 45 to 64 age range.

Fatalities are more than double the 50 deaths reported last week, and include six children under five, nine aged five to 14 and 70 people aged 15 to 64.

The health secretary, Andrew Lansley, who has been criticised for not running an immunisation advertising campaign towards the end of last year, was not present at the government flu briefing.

Labour again accused him of being to slow to respond to complaints about a lack of information and vaccine supplies.

The government's Health Protection Agency stressed that although the death toll had risen sharply, "most of these deaths did not occur in the past week".

"A substantial number of these 62 deaths occurred in December, but due to the backlog over the holiday period they have only been confirmed this week." The overall total of people who have died as a result of seasonal flu is likely to be higher still, the HPA added.

"These figures represent only a proportion of those who may have died from flu or complications from flu, such as pneumonia, over the current flu season," it said.

"Precise figures for flu-related deaths each winter are not available, but estimates based on excess all-cause mortality figures are typically in the region of 0-5,000, predominantly in people over 65 years of age."

Today the father of three-year-old Lana Ameen, who died after contracting swine flu, tells the Daily Mail that cost was the only reason the vaccine was being denied to young children. Registrar Zana Ameen said: "As a doctor, I can't think of any medical reason not to make the vaccine available to young children. The only reason can be cost"

David Salisbury, the health department's director of immunology, did not blame GPs for the failure to reach millions in at-risk groups such as the over-65s, those with underlying health problems or pregnant mothers. "It is extremely difficult to get this message that people under 65 [at risk] do benefit from being vaccinated," he said.

Figures from the HPA suggested nearly 71% of over-65s have now had the vaccine, but only 46% of under-65s, pregnant mothers or people with underlying health problems. Supplies of the 2009 H1N1 swine flu vaccine are being delivered to areas where there had been problems in getting this year's jab. It includes swine flu protection because it is still among the main circulating strains.

"There is no reason for anyone to be turned away on the basis there is no vaccine available," Salisbury said.

John Healey, the shadow health secretary, said: "The big jump in deaths and the high numbers seriously ill in hospital suggest we're still not through the worst of this flu outbreak ... the health secretary should immediately seek the views of frontline doctors on whether to run an advertising campaign to boost the flu jab take-up and on whether to offer the surplus swine flu vaccine to young children.

The overall rate of weekly flu consultations in England has risen from 98.4 to 108.4 per 200,000, but the previous two weeks included public holidays. The latest figure is below the 124.2 peak this season in the week leading up to Christmas. Seventeen people with flu have died in Scotland in the past week, Health Protection Scotland (HPS) said