If national statistics hold true for Missoula County, about 7 percent of residents have had H1N1 flu.

More than twice that number probably believe they've had the new strain of flu. In fact, they've probably had one of any number of respiratory viruses that seem like the flu.

"It's certainly less than 50 percent - the people who've really had it compared to those who thought they had it," said Greg Oliver, health promotion director at the Missoula City-County Health Department. "We know this through sites tracked by the CDC and by our own state lab running tests here. And actually, their number is closer to a third."

The reason that matters is that there are a host of folks who think they've had the disease and are now immune.

But they're not.

Oliver said that health experts think H1N1 flu will eventually affect 20 percent to 30 percent of the population during the current flu season.

"Our cases are trending down right now, but the numbers suggest we'll see another increase and that we're going to see a lot more cases," Oliver said.

That's why the health department is making an extra push to get people into a series of upcoming vaccination clinics (see accompanying story).

"We're really trying to get as many people as we can in our at-risk groups in for a vaccine," Oliver said.

The department has vaccinated about 8,600 people so far, but health officials have another 8,500 vaccine doses on hand and are looking to dispense them in the next few weeks.

The clinics will focus on all at-risk populations, from the very young to the pregnant to those with chronic health conditions.

"By mid-December, I think we will be looking at vaccinating the general population," Oliver said. "But for now, we really want to hit the at-risk groups. We've seen clinics in the Flathead and Ravalli (counties) slow down a little bit, so we're hoping to get the message out that this is still important."

Joe Knapp, a doctor and member of the Missoula County Public Schools board of trustees, stressed Oliver's point.

"Two of the high-risk groups are represented in the school district, with school kids and young teachers who may be pregnant," Knapp said. "I think from a public health perspective, we have to do all we can to protect those populations."

Knapp noted H1N1's propensity to strike young folks compared to seasonal flu, which affects older people more severely.

"We've taken a strong position in the schools, taking kids out of class if they're showing signs of a fever," Knapp said. "I think that level of caution is called for. There haven't been a lot of deaths of school-age children, but if we can prevent anything from becoming serious, we should."

Overall, H1N1 cases are relatively mild, and Oliver said the strain has proved less deadly than the seasonal flu, which kills about 40,000 Americans per year.

Oliver said H1N1 has been hard on people with diabetes. Because 7.3 percent of Americans are diagnosed with the disease and another 2.9 percent have it but are undiagnosed, he stressed the importance of vaccinations.

"That's thousands of people in Missoula County, and we'd like to help them out," Oliver said.

H1N1 has taken the lion's share of flu news this year, but Oliver noted that the seasonal flu season is slowly descending. Health officials will watch with fascination what will happen as the two strains affect various populations.

"Nobody really knows how that's going to play out," he said.

Vaccine for seasonal flu has been scarce recently - most cite the efforts by drug companies to manufacture H1N1 vaccine as a reason - but Oliver said 10 million doses are about to be released.

"How much of that makes its way to Missoula County, we have no idea," he said. "But seasonal flu is still a force to be dealt with, so if people haven't been vaccinated, they should be on the lookout for the chance to do that, too."