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During the height of the H1N1 influenza alert, a small team of Minnesota Department of Health  epidemiologists worked late into the night, testing hundreds of patient specimens that were sent to the state laboratory. 

They were looking for signs of the new flu strain. But what they mostly found was regular seasonal flu. 

Of the approximately 493 specimens tested, there was one confirmed case of H1N1 and 11 probable cases. Thirty-three samples matched seasonal flu.  

That's more seasonal flu cases than MDH epidemiologist Kris Ehresmann would have expected this late in the year. Perhaps it's normal and the state's heightened surveillance finally detected it, according to Ehresmann.

"The H1N1 novel influenza really drew our attention to influenza, at a time when we normally don't think about it. And it drew attention both on the part of the clinician community, as well as the labs for testing. And so we're picking up things that we normally would not have," Ehresmann said.  

As far as flu seasons go, H1N1 aside, this was a fairly unremarkable year. The strains in circulation were mild and there have been no pediatric deaths in Minnesota -- breaking a troubling trend in recent flu seasons. 

Changes in the state's vaccination guidelines have probably made a difference, Ehresmann said. 

"Whereas in the past only a portion of children were recommended for vaccination, now all children from 6 months through 18 years are recommended to receive an influenza vaccine. So that was a new twist to this year's influenza season," she said. 

The state doesn't track adult deaths from seasonal flu. But the Health Department estimates that each year 700 to 800 Minnesotans, mostly elderly, die from complications from the virus.

Reports from nursing homes appear to reinforce the idea that this was a mild year for flu.  There were fewer long-term care facilities that reported outbreaks among their patients, the Health Department said. 

What  does this influenza season suggest about how flu might unfold next fall? 

With H1N1 now in the mix of flu strains, the situation is even more unpredictable, according to Greg Filice, Chief of Infectious Diseases at the Veterans Affairs Hospital in Minneapolis.

"Unless things change with the virus, I think the best guess is disease next winter will be similar to what we're seeing now," said Filice. "So if we see disease next year, there's no reason to expect that it would be a lot different -- although this virus can mutate and recombine, and so we can't totally be sure."  

Infectious disease experts will be watching the southern hemisphere closely for signs that H1N1 virus is changing. Flu season there has just begun and will continue through September.

Already, though, scientists say they have learned a lot about the new strain of influenza. Certain genetic patterns that are known to cause very severe disease in other strains of flu are not present in H1N1, Filice said, which is reassuring.

"I don't think anybody would tell you that we know what all the potential severe patterns of genetic sequences are. So there may be a particularly severe sequence that we've never seen, and that we don't know how to recognize. But again, we haven't seen the patterns that have been associated with severity in the past," said Filice. 

While that's likely reassuring to some Minnesotans, public health officials don't want the public to get the impression that a severe pandemic is no longer a threat. 

It's inevitable that each time a pandemic does not materialize, the public becomes a little less concerned, said Peter Sandman, a New Jersey-based risk communicator.

"They warned about bird flu a few years ago and it didn't happen yet. They warned about swine flu last week, and it happened so barely invisible so far," said Sandman.  

Sandman doesn't fault public officials for sounding the alarm during the H1N1 flu outbreak.  They did exactly what they are supposed to do, he says. He worries that some officials might be tempted to tone down their message this summer.

"There's no question that national government will use the calm to become better prepared. But will they ask us to? And if they do, will we listen? Those are tough questions," Sandman said. 

Sandman says he's not sure he would want to stake his reputation on something that may or may not materialize anytime soon. But he says that's exactly what public health leaders and politicians should be doing when it comes to the threat of pandemic flu.

Gallery

Two more probable flu cases in Minneapolis

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Lorna Benson

Author

The new H1N1 influenza outbreak occurred just as the seasonal flu typically fades in Minnesota. The state's heightened flu surveillance due to H1N1 showed that seasonal flu may be lingering a bit longer than usual this year.

H1N1 outbreak revealed seasonal flu lingered in Minn.

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