NEW YORK — More U.S. children have died this flu season than at any time since the swine flu pandemic 15 years ago, according to a federal report released Friday.

The 216 pediatric deaths reported by the Centers for Disease Control and Prevention eclipse the 207 reported last year. It’s the most since the 2009-2010 H1N1 global flu pandemic.

It’s startling that the number already is this high, given that the flu season is still going on. The final pediatric death tally for the 2023-2024 flu season wasn’t counted until autumn.

“This number that we have now is almost certainly an undercount, and one that — when the season is declared over, and they compile all the data — it’s almost certain to go up,” said Dr. Sean O’Leary of the American Academy of Pediatrics.

There are likely several contributors to this season’s severity, but a big one is that fewer children get flu shots, added O’Leary, a University of Colorado pediatric infectious diseases specialist.

The flu vaccination rate for U.S. children has plummeted from about 64% five years ago to 49% this season.

Flu vaccinations may not prevent people from coming down with symptoms, but research shows they are highly effective at preventing hospitalizations and deaths, O’Leary said, adding that the decline in vaccinations “is certainly playing a role” in this season’s loss of life.

The season has not only been hard on children. CDC officials have described it as “ highly severe,” and estimate that so far there have been at least 47 million illnesses, 610,000 hospitalizations and 26,000 deaths this season.

The good news is that flu indicators have been waning since February.