By Fergus Walsh
Health correspondent, BBC News
Health officials in Cardiff are investigating the possible person-to-person spread of a Tamiflu-resistant strain of swine flu.
The strain has infected a small number of patients at the University Hospital Wales, all of whom have serious underlying health conditions.
If confirmed it would be the first case of its kind in Europe.
It appears one person developed resistance, and the strain was then passed on to others at the hospital.
There have been several dozen reports around the world of people developing resistance to tamiflu whilst taking the drug.
But what happened at the University Hospital Wales – person to person transmission – may be quite different.
There has been only one other similar case in the US among two people at a summer camp – but the resistant strain did not spread any further.
Health officials in Wales said more tests were being carried out to confirm exactly what happened.
They are not yet confirming person to person spread.
All the patients are said to recovering and being cared for in controlled environments so there is no risk to anyone else.
Tamiflu is an antiviral and can reduce the risk of complications of flu as well as shortening the duration of illness.
The UK has enough doses for half the population.
Any spread of a Tamiflu resistance strain of swine flu would be a serious public health concern, but there is no evidence to suggest that this has happened.</p
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