It's a scenario that strikes terror in most any parent: A perfectly healthy first-grader dies of flu in the ambulance outside his home. How could it happen?

In the most recent H1N1 flu death in Minnesota, the Hennepin County Medical Examiner's office said that 6-year-old Nathanael Schilling of Corcoran died on Sept. 24 from an inflammation of the heart, a rare complication that can result from a flu infection.

He was a first-grader at St. John's Lutheran School in Corcoran, according to his newspaper funeral notice.

It was the seventh death from H1N1 in Minnesota, and the second time this year that an otherwise healthy child died after becoming infected with the new flu strain.

Health officials say they still expect the new virus to be no more deadly than ordinary seasonal flu, which kills 36,000 Americans in an average year. What's different this year is that children appear to be more vulnerable to the new strain than to seasonal flu.

The previous child fatality in Minnesota, which occurred in July, also involved an otherwise healthy child. That 2-year-old died because of a co-occurring bacterial infection -- pneumococcus, which causes pneumonia, said Dr. Ruth Lynfield, Minnesota state epidemiologist.

Alone, it's not usually dangerous in someone who is healthy. But the flu virus opens a door, allowing the non-threatening agent to overwhelm the body and become lethal. It's the combination of the two that often kills otherwise healthy children and adults.

If symptoms worsen, act

"That's why we tell people who get the flu that if they are getting better and then symptoms get worse with high fever and bad cough, they should seek care right away," Lynfield said.

A recent study by the Centers for Disease Control and Prevention (CDC) found that of the 36 children who died from H1N1 from April to August, six had no chronic health conditions. But all of them had a co-occurring bacterial infection.

The most common co-occurring infection that causes flu-related deaths is staphylococcus aureus, commonly known as staph, said Pat Schlievert, a microbiologist at the University of Minnesota and an expert on staph-related deaths. A third of the population carries it on their body, most in their noses or on their skin. Often it's benign or causes minor skin infections. Schlievert has studied dozens of cases of children who died unexpectedly from flu combined with staph.

"The [flu] causes upper respiratory damage, which allows the staph to get where it's not supposed to be. It makes it's way into the lungs," he said.

So far in Minnesota three of the seven deaths from H1N1 have been children and only the first, who died in June, had an underlying health problem that put her at greater risk. The other deaths were adults, one elderly, and three middle-aged, all with chronic health conditions such as asthma, obesity or suppressed immune systems.

That's a sharp contrast to the pattern of fatalities seen with seasonal influenza. Most years, 90 percent of the people who die from complications of flu are elderly, and most others have chronic health problems that make them vulnerable.

Most recover

The vast majority of people who become infected with H1N1 recover, Lynfield said, "but some do get severe disease."

The good news this week is that vaccine has arrived in Minnesota.

The first shipment of nasal spray vaccine was distributed to staff at some hospitals, including Children's Hospitals of Minneapolis and St. Paul, and some area public health agencies. The rest of the first order of 28,000 doses is expected to arrive throughout the rest of the week.

The nasal vaccine, which contains a live virus, is going to health care workers, who are third on the priority list for vaccine distribution. It's not safe for the two groups at the top of the list, young children or pregnant women, who are considered most at risk.

Health care workers are at high risk of exposure to the virus, and are in a position to infect vulnerable patients.

Injectable vaccines, which will go to those high risk groups first, are not expected to arrive in the state until mid-October.

In the meantime, however, clinics are already gearing up for the deluge of people who want the vaccine. "People are asking about it," said Dr. Ron Jankowski, medical director of the Fremont Clinics in Minneapolis.

Like many clinics across the country, Fremont now has a prompt on its phone line that leads patients to a long message about seasonal flu and H1N1 vaccine.

Federal health officials have said that more than 150 million doses of vaccine will be available nationally, meaning everyone who wants the vaccine should be able to get it.

"The question is, will [swine flu] come and go before the vaccine is available to everyone?" said Jankowski. "Who knows?'

Josephine Marcotty • 612-673-7394