A form of swine flu that is resistant to antiviral drugs has begun spreading between hospital patients in Wales, health officials said.
A strain that appears resistant to Tamiflu, the most common treatment has infected five patients at the University Hospital of Wales in Cardiff. All of them had serious underlying health conditions.
One patient apparently developed resistance to the antiviral drug and the strain was then passed on to others, the National Public Health Service for Wales (NPHS) said. The case is thought to be the first time in Europe that a drug-resistant strain has passed between people.
Two of the five patients have recovered and been discharged from hospital, one is in critical care and two are being treated on the ward. Britain has bought enough doses of Tamiflu, which can shorten the duration of swine flu and reduce the risk of complications, for half of the population.
There have been several dozen reports around the world of people developing resistance to Tamiflu, but there has been only one case of person-to-person transmission of a Tamiflu-resistant strain, between two people at a summer camp in the United States.
The Department of Health said that it was taking the cases seriously, but added that the risk to the general population was low.
“The Tamiflu-resistant virus has emerged in a group of particularly vulnerable individuals . . . these patients are known to be at increased risk of developing resistance to the drug, a spokesman for the Department of Health said.
“Our strategy to offer antivirals to all patients with swine flu is the right one — to help prevent complications and reduce the severity of the illness.”
The NPHS said that the resistant strain did not appear more severe than the virus circulating since the spring. All patients have been tested and those with the resistant strain have been given other antivirals.
Dr Roland Salmon, director of the NPHS Communicable Disease Surveillance Centre, said: “The emergence of influenza A viruses that are resistant to Tamiflu is not unexpected in patients with serious underlying conditions and suppressed immune systems, who still test positive for the virus despite treatment.
“In this case, the resistant strain of swine flu does not appear to be any more severe than the swine flu virus that has been circulating since April. For the vast majority of people, Tamiflu has proved effective in reducing the severity of illness.
“Vaccination remains the most effective tool we have in preventing swine flu so I urge people identified as being at risk to look out for their invitation to be vaccinated by their GP surgery.”