SCIENTISTS estimate fewer people will die in the flu pandemic in the UK than initially feared.

Officials said the number of fatalities would range between 3,000 and a worst case of 19,000 – down from 65,000 reported in July.

Chief medical officer Sir Liam Donaldson said the revised figures were "assumptions and not predictions" and did not include an assessment of what impact the swine flu vaccine may have.

The 19,000 toll is based on 30 per cent of people being affected and a death rate of 0.1 per cent and reflects latest evidence the virus is weaker than others.

An estimated 4,500 people were newly diagnosed with swine flu in England in the last week, down from a high of around 100,000 cases.

There have been 61 deaths in England, up from 57 last week. There have been 70 UK deaths overall.

Around 150 people are being treated in hospital for flu-like infections.

A paper in the British Medical Journal says health officials responded to the outbreak of swine flu as if it was an "unfolding disaster". The response may now be seen as "alarmist, overly restrictive, or even unjustified" and it calls for a change of approach to future threats to public health.

However, experts have predicted a surge in the number of swine flu cases with the reopening of schools and universities after the summer break.

Meanwhile, a pilot study of a swine flu vaccine has revealed a "strong immune response" after just one dose.

Trial leader Iain Stephenson, of Leicester University, found 80 per cent of the volunteers showed a "strong, potentially protective" response after one dose, with more than 90 per cent showing the same response after two.

He said: "The results suggest that one vaccine dose may be sufficient to protect against A(H1N1) swine flu, rather than two."

The first vaccinations of people in at-risk groups – such as those with asthma and diabetes – are expected to take place next month.

Sir Liam said more work was needed to see if the Leicester findings were replicated across other studies.

"The work on the H5N1 virus (avian flu) did suggest that you needed to have both doses to get a proper antibody response," he said. We will watch carefully but we are certainly, at this stage, not starting to think about one dose rather than two."

Companies have been warned to prepare for up to half their staff being off sick for two to four weeks in a second wave of swine flu. The Chartered Institute of Personnel and Development (CIPD) and the Business Continuity Institute said businesses should be prepared for a significant increase in absence rates.

Ben Willmott, of CIPD, said: "The media and public hysteria sparked by the initial stage of the pandemic has created a cry wolf effect where the temptation for business leaders is to ask what all the fuss was about and get on with the priority of competing and surviving in recession.

"Evidence shows that still only a minority of employers have an adequate contingency plan in place to deal with a flu pandemic, which is extremely worrying considering that staff absence levels could peak for some businesses at levels which will make business as usual extremely difficult."