State health officials annouced late Friday that three of four people infected with drug-resistant H1N1 have died at Duke University Hospital.

The four patients tested positive for what officials said is a mutation of H1N1 that is resistant to Tamiflu, one of two medications used to help fight the virus. The patients were diagnosed with the flu during October and November and all were hospitalized in the same unit at Duke University Medical Center.

"We are unable to say if their deaths were caused by influenza," said Dr. Megan Davies, NC State Epidemiologist. "They're influenza associated but they had medical issues that were compromising their health."

Officials said there appears to be no difference in severity between this new mutation and the typical H1N1 virus that has been circulating.

"This resistance is from a mutation but it doesn't mean H1N1 in general is mutating," said Dr. Zack Moore, Medical Epidemiologist with the Division of Public Health. "It's a mutation that has occurred in a small number of patients."

So small a number that health officials said Tamiflu is still a very effective medicine in treating H1N1. They are assessing with Duke and the CDC to determine what, if any, connections there may be between the patients. The patient still at Duke was also treated with the drug Relenza and officials said she is recovering. Officials said no resistance has been found against Relenza, the other drug used to treat H1N1.

"The vast majority of people with influenza do not even receive antiviral treatment," said Dr. Davies. "This mutation is a moot point for most of us, however, it is something we have to pay attention to when we see it."

Dr. Cameron Wolf with Duke's Infectious Disease Department said these cases have not changed treatment policies at Duke, although it is something they're at least evaluating.

Health officials said these recent cases should be a reminder for people in the high-risk categories to get vaccinated.