A new drug-resistant “super-flu” has become increasingly common and may pose a serious risk to hospital patients, scientists have warned.

Two research papers published in the Journal of the American Medical Association show that a drug-resistant mutation of the H1N1 influenza A virus, a strain that causes common seasonal outbreaks, has spread rapidly round the world.

The subtype cannot be treated with the antiviral drug oseltamivir, sold as Tamiflu, which is one of the first lines of defence for those most vulnerable to flu.

Scientists said the studies showed that the virus was a particular threat to people in hospital with weakened immune systems, and underlined the need to develop new drug treatments and improve staff vaccination rates.

The two papers, by American and Dutch research teams, come amid concerns about the prevalence of flu in healthcare premises in Britain and the failure of NHS staff to get immunised.

The Times revealed on Saturday that Department of Health data, to be published this month, shows that only 14 per cent of health workers had a flu jab last year, despite warnings from NHS leaders that all must do so to minimise the risk of the disease spreading.

A flu outbreak in December at Royal Liverpool University Hospital in December led to almost 100 patients – many in high-dependency wards for blood diseases and kidney problems – and 20 staff being infected with the virus.

It was identified as a Tamiflu-resistant strain and a second medication had to be used to treat and protect patients and control the outbreak.

The Health Protection Agency, which commended Royal Liverpool’s rapid response, said that it was a timely warning of how easily flu can spread when the virus is circulating in the community and staff vaccination levels are low. The latest flu vaccine does offer a degree of coverage against Tamiflu-resistant strains.

The Dutch research team led by Jairo Gooskens, from Leiden University Medical Centre, said that the rapid spread of resistant H1N1 flu strains had been observed since January last year. Viruses with the gene mutation, labelled H274Y, were originally thought to be less virulent and less easily transmitted.

Dr Gooskens told The Times that his study emphasised the need for high vaccine use by frontline health workers and the vulnerability of patients with compromised immune systems.

“The new finding that oseltamivir-resistant influenza A(H1N1) virus can cause [healthcare acquired] outbreaks, as apparently occurred in the UK as well, merely adds to the urgency to expand the overall rates of influenza immunisation among healthcare workers," he said.

"In the light of convincing evidence of clinical benefits regarding influenza vaccination among healthcare workers, the reason for low vaccine uptake remains enigmatic.”

The US team led by Nila Dharan, from the Centres for Disease Control and Prevention in Atlanta, Georgia, found that 12 per cent of influenza A (H1N1) viruses tested during the 2007-08 flu season were resistant to Tamiflu.

But preliminary findings from the 2008-09 season suggested much higher levels of Tamiflu resistance. As of February 19 this year, resistant strains had been identified among 264 out of 268 — or 98.5 per cent — of influenza A (H1N1) viruses tested in the US.

The researchers examined data on 99 people infected with Tamiflu-resistant flu during the 2007-08 influenza season. Five patients were hospitalised and four died.

“The emergence of oseltamivir resistance has highlighted the need for the development of new antiviral drugs and rapid diagnostic tests that determine viral subtype or resistance, as well as improved representativeness and timeliness of national influenza surveillance for antiviral resistance,” the scientists wrote.

In an accompanying editorial, David Weinstock, of the Dana-Farber Cancer Institute, Boston, and Gianna Zuccotti, of Brigham and Women’s Hospital, Boston, said that the spread of Tamiflu-resistant flu came as a great surprise. “Undoubtedly, surprises await in the struggle with influenza as one thing is certain – the organism will continue to evolve,” they said.

— The National Institute for Health and Clinical Excellence, the medicines watchdog, must become better at identifying promising drugs and have more independence from Whitehall if patients are to get quicker access to the latest therapies on the NHS, ministers will say today. The institute can take two years to approve a drug but ministers want to cut this to six months.

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