(HealthDay)—This past flu season started earlier, peaked earlier and led to more adult hospitalizations and child deaths than most flu seasons, U.S. health officials reported Thursday.
At least 149 children died, compared to the usual range of 34 to 123, according to the U.S. Centers for Disease Control and Prevention.
The predominant strain of flu circulating in 2012-13—H3N2—made the illness deadlier for children, explained Lynnette Brammer, an epidemiologist with the CDC.
"With children H3 viruses can be severe, but there was also a lot of influenza B viruses circulating . . . and for kids they can be bad, too," she said.
Dr. Marc Siegel, an associate professor of medicine at NYU Langone Medical Center in New York City, added that H3N2 is easily transmitted from person to person and has a high rate of complications, which accounts for the increased hospitalizations.
"This is the kind of flu that enables other infections like pneumonia," he said. "Really what people need to know is that flu isn't the problem. The flu's effect on the immune system and fatigue is the problem."
The flu season started in September, which is unusually early, and peaked at the end of December, which is also unusual, Siegel said.
Flu season typically begins in December and peaks in late January or February.
Texas, New York and Florida had the most reported pediatric deaths. Except for the 2009-10 H1N1 flu pandemic, which killed at least 348 children, the past flu season was the deadliest since the CDC began collecting data on child flu deaths, according to the report, published in the June 14 issue of the Morbidity and Mortality Weekly Report.
Older adults were targeted heavily by the 2012-13 flu. Those aged 65 and older accounted for more than half of all reported flu-associated hospitalizations in the 2012-13 flu season—the most since the CDC started collecting data on flu hospitalizations in 2005-06, the agency reported.
In addition, more Americans saw a doctor for flu than in recent flu seasons, the CDC noted.
The flu vaccine was well matched to the circulating strains, but less effective than health officials had hoped. In January, the CDC reported that the vaccine was about 60 percent effective, which meant it offered "moderate" protection from the flu.
Siegel said even a moderately effective vaccine is better than not getting vaccinated at all because flu symptoms will be milder, with a lower chance of complications.
According to Brammer, decisions about the vaccine for this coming season were made in February so manufacturers could make a sufficient supply for fall. The makeup will be basically the same as the 2012-13 vaccine with some tweaks to some of the strains so they better match changes in the viruses, she said.
The CDC recommends that everyone 6 months and older get vaccinated. The agency urges people at higher risk for severe disease—including young children, pregnant women, anyone with a chronic health problem and the elderly—to get the vaccine.
Don't make any assumptions about the course of next season's flu based on the recent past, these experts added.
"I wouldn't assume next year's flu season is going to be milder or that it's going to be early," Siegel said. "The flu is unpredictable."
Because the 2012-13 flu season started several months earlier than usual, the CDC also advised doctors to consider influenza as the source of respiratory illnesses that occur beyond the typical flu window.
Explore further: CDC: 105 US children died this flu season
For more information on flu, visit the U.S. Centers for Disease Control and Prevention.