A 14-year-old Naperville girl who died Thursday, Oct. 8 tested positive for swine flu, marking the first death in DuPage County from the new strain of the H1N1 virus.

The county coroner’s office is still investigating the cause of death, but health officials announced Friday that it was related to swine flu. There might also have been another health condition, officials said.

Most of the people who contract the H1N1 flu will fully recover, said David Hass, a spokesman for the DuPage County Health Department. But it tends to have more of an effect on people younger than 24 and those with an underlying condition.

More than 1 million H1N1 flu cases have been reported in the United States, and 19 people in Illinois have died this year.

Hass said health officials expect many more illnesses and possibly more deaths during the coming flu season.

“It’s probably everywhere,” he said. “That’s exactly why we’re encouraging more people to get vaccinated right now.”

The health department expects to receive its first shipment of tens of thousands of swine flu vaccines within a few weeks, Hass said. Some of the shots will go to health care providers and some will be distributed directly at the county health offices.

“So it gets to the largest number of people as fast as possible,” Hass said.