The number of people consulting their GP because they think they have swine flu has almost doubled in one week, figures showed.
The Department of Health said an estimated 100,000 people in England sought help in the past week, up from 55,000 the previous week.
There are now 840 people in hospital with the virus, of which 63 are in intensive care.
Most people with the virus in hospital are aged 16 to 64, with 435 cases, followed by the under-fives, with 169 cases.
Among those aged over 65, 149 people are in hospital and there are 87 cases among young people aged five to 15.
Tower Hamlets in east London continues to be the primary care trust with the highest number of GP consultations for people with flu-like illness.
It is seeing 792 consultations per 100,000 people, followed by Islington in north London with 488 consultations per 100,000.
Other badly affected parts of England include Greenwich, south east London, Leicester, and Telford and Wrekin.
The Government's chief medical officer for England, Sir Liam Donaldson, said information on the number of deaths in England had now been provisionally validated.
This means each death has been fully investigated to determine whether somebody had swine flu and to what extent it may have contributed to their death.
He said there were 26 deaths in England that were now provisionally validated, which is the same figure as last week.
But Sir Liam would not be drawn on how many of those deaths were new and how many deaths had been discounted in the new calculations.
"Some have gone out and some have come in," he said. "We are down to the sorts of numbers where it might be possible to identify individuals."
Asked whether the flu pandemic had reached its peak in England, he said: "We just really don't know."
Asked why the UK seemed to be particularly badly affected by the flu epidemic compared with the rest of Europe, Sir Liam said it could be that the UK had better surveillance systems for picking up the number of cases.
"We also have strong travel links with North America, then I probably think there's an X-factor, it might be just that the eco system for the virus here is different to other countries.
"There's an unpredictability and inexplicability about the flu virus."
Four people are known to have died with the virus in Scotland.
