British, Welsh agencies investigate possible Tamiflu-resistant H1N1 cases

LONDON -- Britain's Health Protection Agency is working with colleagues from the Public Health Service of Wales to investigate several possible cases of person-to-person transmission of oseltamivir-resistant H1N1 flu, the agency reported Nov. 20.

To date, nine H1N1-confirmed cases have been reported among patients at a hospital in Wales. Five of these cases are known to be resistant to oseltamivir, one is sensitive and for three, their resistance status is unknown.

Oseltamivir is also known by the brand name Tamiflu

The virus has emerged in a group of particularly vulnerable individuals in whom the development of oseltamivir resistance is well documented. Health officials said they do think the risk to the general healthy population is low. There is no evidence that the oseltamivir-resistant virus is any more virulent than any other type of flu, they said. The situation is being kept under review.

Further follow-up of cases and their close contacts both at the hospital and in the community is under way to ascertain if there is evidence of further transmission. The virus remains sensitive to the other frontline drug Relenza, which is being used as an alternative antiviral and patients are responding well.

Although further epidemiological investigation is underway, it would seem likely that transmission of oseltamivir-resistant H1N1 virus has taken place.

The current cases of oseltamivir resistance under investigation have all occurred in patients with problems that result in immune-system suppression.