Flu outbreaks soared in Minnesota schools before most students left their classrooms for winter break, another sign that this year’s flu strain is hitting young people harder than a year ago.

One child died during the week, the third such flu-related death of the season among Minnesotans under 18. Last year’s influenza season produced no flu-related deaths among Minnesota kids. The most recent fatality was a child, not an infant, who had an underlying health impairment, a state health official said.

Reporting its weekly flu update for the seven days that ended Dec. 20, the Minnesota Department of Health said a startling 281 new flu outbreaks were counted in Minnesota schools, a 38 percent increase from the previous week.

That came close to the state record of 288 weekly school outbreaks set in the 2009-10 influenza pandemic, said Kris Ehresmann, director of epidemiology for the health department.

“We’re seeing very severe and aggressive influenza activity this year,” Ehresmann said.

Altogether this season, Minnesota schools have reported 543 outbreaks of flu-like illnesses. Schools report an outbreak when the number of students absent with flu symptoms reaches 5 percent of total enrollment or when three or more students with flu-like illness are absent from the same elementary classroom.

Ehresmann said the health department is expecting fewer outbreaks when school resumes, because the winter break in school activity will reduce transmission and sick children will have time to recover.

As in previous weeks, the health department’s surveillance showed flu to be widespread in Minnesota, meaning more than half the state’s monitoring districts. The report indicated only five hospitalizations for the week, compared with 119 in the previous week. But Ehresmann said the drop-off was a fluke due to reporting difficulties, not a respite from illness.

To date, more than 380 Minnesotans have been hospitalized with the flu, according to the health department.

This year’s dominant flu strain is H3, a strain that has historically been hardest on the elderly and on very young children. The weekly report also showed a sharp increase in outbreaks in Minnesota nursing homes and other long-term care facilities. There were 31 new outbreaks reported during the week that ended Dec. 20, the report said. In the previous week, nursing home facilities reported 18 new flu outbreaks.

“It’s hitting everybody hard this year,” Ehresmann said.