Viral samples taken from patients in Hawai'i indicate that common flu bugs now making the rounds are resistant to the popular flu medicine Tamiflu.

It's too early to know whether the resistant strains of influenza A (H1N1) will become the prevalent viruses of the 2008-2009 flu season, but health officials say the preliminary data underscore the importance of getting a flu vaccination sooner rather than later.

"Even though they are resistant to antiviral treatment, those viral strains are covered under this year's flu vaccine. The best thing still is to get the shots that will prevent you from getting sick in the first place," said Michele Nakata, head of the state Department of Health's Disease Investigation Branch.

"Now is really a great time to get a flu shot, especially with Christmas and New Year's and all the gatherings."

The U.S. Centers for Disease Control and Prevention issued an advisory on Dec. 19 to physicians warning that the most common flu bugs spreading in the United States are resistant to the antiviral medication oseltamivir, sold under the brand name Tamiflu.

The strains have been detected in 12 states so far, mostly in Hawai'i and Texas. Of the 50 H1N1 strains tested since October, 49 were resistant to oseltamivir, the CDC reported.

Officials said there is no indication the oseltamivir-resistant viruses cause more severe symptoms than strains that are sensitive to the medication. Tests also show the resistant strains are susceptible to other flu treatments, such as zanamivir, sold under the brand name Relenza, and the older drugs amantadine and rimantadine.

"It is still very early in the season. There is very little influenza out there," CDC director Dr. Julie Gerberding told reporters in a telephone briefing Friday. "This is probably actually not going to affect very many people because we don't use a lot of antiviral drugs in our country. Most people with influenza don't get any treatment."

There are three types of human flu viruses that circulate worldwide: two influenza A subtypes, H1N1 and H3N2, and influenza B. There is no way to predict how prevalent the resistant strains will be or when and where they will strike.

During the last flu season, 11 percent of H1N1 strains were found to be resistant.

As a result of the recent findings, the CDC issued interim recommendations for antiviral treatment of influenza during the 2008-09 influenza season calling for use of zanamivir or a combination of oseltamivir and rimantadine, instead of oseltamivir alone, when H1N1 virus infection or exposure is suspected.

So far this season, influenza activity has been low in the United States, according to the CDC.

For the week ending Dec. 13, the agency reported "local flu activity" in only Hawai'i, Massachusetts and Texas, meaning there were outbreaks in a single region of the state. In Hawai'i, an outbreak occurred at an unnamed school on O'ahu where influenza A was detected, according to the Health Department's influenza surveillance report for the week.

During that same period, 24 states reported sporadic cases and 23 reported no flu activity.

Nakata said flu activity in Hawai'i is "on the low side" and that the reports surrounding the Hawai'i viral samples are more indicative of the state's high level of participation in the viral monitoring program than in the actual number of flu cases.

"It doesn't mean we are experiencing unusual or higher than usual flu cases. It's that we are one of the better participants," she said.

Influenza causes approximately 226,000 hospitalizations and 36,000 deaths annually in the United States. Health officials say annual vaccination remains the best method for preventing influenza and its potentially severe complications.