From the Boston Globe (boldface mine):
Roughly 100 children die in an average flu season. One exception was the swine flu pandemic of 2009-2010, when 348 children died.
The CDC recommends that all children ages 6 months and older be vaccinated against flu each season, though only about half get a flu shot or nasal spray.
All but four of the children who died were old enough to be vaccinated, but 90 percent of them did not get vaccinated, CDC officials said.
This year’s vaccine was considered effective in children, though it didn’t work very well in older people. And the dominant flu strain early in the season was one that tends to cause more severe illness.
If this doesn’t convince people to get vaccinated, I don’t know what will. Because someone infected these children, and the odds of that happening decrease when more people are vaccinated.