H1N1 pandemic swine flu is far less lethal than feared, British scientists said on Wednesday, but public health officials should not be complacent in fighting it and vaccination campaigns should continue.

The first comprehensive analysis of deaths from swine flu in England since the H1N1 virus was declared a pandemic in June shows there are 26 deaths in every 100,000 cases of swine flu -- a death rate of 0.026 percent.

The study echoes U.S. research published on Monday which found the H1N1 pandemic had a death rate of 0.048 percent, or 1 death in 2,000 cases -- only a little more serious than an average flu season.

The first influenza pandemic of the 21st century is considerably less lethal than was feared in advance, England's chief medical officer Liam Donaldson wrote in the study carried out by his team at the government's Health Protection Agency.

The researchers said their fatality rate estimate compared well with three 20th century flu pandemics -- the rate for the 1918 Spanish flu was 2 to 3 percent and subsequent pandemics in 1957/8 and 1967/8 had rates of around 0.2 percent.

Donaldson said improvements in nutrition, housing and health care might explain some of the apparent decrease in case death rates from one pandemic to the next.

Since the most recent pandemic there have been major advances in intensive care medicine, he added, and many more may have died without critical care services such as machines to ventilate patients with breathing difficulties.

The study should allay fears among public health officials and policymakers that a flu pandemic could kill millions around the world and push economies deeper into recession. It may also add to suspicions that health officials and the drug industry hyped the threat posed H1N1.

Swine flu has killed 10,074 people worldwide since it was declared a pandemic in June, according to the European Center for Disease Prevention and Control. Experts say seasonal flu can kill up to 40,000 people a year in Europe alone.

Donaldson said the analysis showed two-thirds of those who died from H1N1 would now be eligible for vaccines under the British government's high-risk-first vaccination priority plan, suggesting the vaccination campaign was still important.

Doctors have been vaccinating high-risk groups such as sick patients in hospital, pregnant women, people with asthma or other underlying health problems and healthcare workers with GlaxoSmithKline's Pandemrix vaccine and Baxter's Celvapan, but uptake has been slow as many see H1N1 as mild.

The government is now extending the vaccination campaign to children under five and Donaldson said there was a case for extending it to the wider population given that a large minority -- 38 percent -- of deaths occurred in non-high-risk groups.

The study was published in the British Medical Journal and includes all known deaths in England from H1N1 until November 8.

It found that in most fatal cases, patients had not started taking antiviral drugs such as Roche's Tamiflu or Glaxo's Relenza until around 5 days after symptoms began.

This finding reinforces the need to use medicines like antivirals and vaccines wherever possible, the researchers said.