CDC confirms 4 new cases of Tamiflu-resistant H1N1

DURHAM, N.C. -- Tests performed by the Centers for Disease Control and Prevention at the request of infectious disease experts at Duke University Medical Center have confirmed that samples from four patients with H1N1 influenza at Duke University Hospital over the past six weeks were found to be resistant to oseltamivir, known by the brand name Tamiflu, Duke announced Nov. 20.

Two oseltamivir-resistant H1N1 isolates were reported in western North Carolina earlier this summer. A team of experts from CDC, State of North Carolina Public Health Department, Durham County Health Department, and the Duke Division of Infectious Diseases are working to better understand the nature of these cases.

All four samples were obtained from four patients in an isolated unit of one floor at Duke University Hospital. All four patients were very ill with underlying severely compromised immune systems and multiple other complex medical conditions.

"We're partnering with all of the involved agencies to examine these cases," said Daniel Sexton, professor of medicine and director of the Duke Infection Control Outreach Network.

"Our extensive investigation thus far has revealed that appropriate infection control procedures have been diligently practiced on this isolated unit, and throughout the hospital, and we have experienced no illness among employees taking care of these patients in the affected unit over this period of time."

According to the CDC, patients with oseltamivir-resistant H1N1 have had similar, no more severe, illness than patients with oseltamivir-susceptible virus.

Furthermore, CDC reports that all confirmed cases of oseltamivir-resistant virus to date have been susceptible to zanamivir, known by the brand name Relenza, a second antiviral medication that is indicated for the treatment of H1N1.

At this time, CDC does not recommend any changes in antiviral guidance.

Aggressive H1N1 vaccination efforts directed to Duke University Hospital's high-risk patient populations and patient care employees will continue as the hospital receives vaccine supply, officials there said.