بوابة المعرفة

New study says kids under age 5 are more at risk of death of flu than others

A CDC analysis of last season's child flu deaths in the Unites States suggests that kids younger than 5 years old are more at risk of severe flu than older ones.

There were 115 confirmed child flu deaths from Sept. 1, 2010, through Aug. 31, 2011. The number includes all infants, children, and teens under age 18.

Children only rarely die of flu. But the illness can be much more severe than most parents think. Just under half of the reported child flu deaths -- 49% -- were in kids with no underlying illness or other risk factor for severe flu.

However, 46% of kids who died last flu season were under age 5. And 29% were under age 2.

"The report underscores the fact that young age is itself a risk factor," a CDC news release notes.

The much larger number of kids who died of flu but were not tested or officially reported is not included in the study, says Lyn Finelli, DrPH, chief of the CDC's surveillance and outbreak response team.

"Many, many pediatric deaths are not reported because not all kids with symptoms of flu are tested. We know this number of reported case is a fraction of pediatric flu deaths."

The CDC report appears in the Sept. 15 (2011) issue of Morbidity and Mortality Weekly Report.

Vaccine not fully effective

More than four out of five kids who died of flu were not fully vaccinated. That is sad, but not surprising. What seems odd is that 23% of the deaths were among kids who were fully vaccinated.

Part of the reason is that most of these fully vaccinated kids had underlying illnesses. The flu vaccine does make most of these children far less susceptible to serious flu. But underlying illness chips away at a person's immune system, making vaccines somewhat less effective than in healthy people.

And 12% of the child deaths were in fully vaccinated kids with no underlying illness. How could this happen?

"There are always vaccine failures," Finelli says. "Say a vaccine is 90% effective. You are going to see those 10% of vaccine failures in statistics on deaths and hospitalizations. It makes you think the vaccine works less well than it does. You never see the vast majority of people for whom the vaccine works."

Kids at highest flu risk

The most common risk factors among kids who died of flu were neurologic conditions. Over a quarter of pediatric deaths (27%) were in such kids. Conditions included:

• Moderate or severe developmental delay: 19% of child flu deaths
• Seizure disorder: 12% of child flu deaths
• Cerebral palsy: 8% of child flu deaths
• Neuromuscular disorder: 4% of child flu deaths
• Other neurological disorders: 7% of child flu deaths

Kids with underlying lung diseases, including asthma, made up 15% of child flu deaths.

Flu drugs given too late

The CDC report identifies a glaring problem with how kids with flu are treated: getting antiviral flu drugs, such as Tamiflu, too late.

Half the kids who died in a hospital or emergency department never received antiviral flu drugs. That's probably because doctors waited for the results of flu tests before ordering the medication.

"They should start antiviral agents even before they test for flu. They can test for flu in the meantime, but antiviral agents save lives. They should be given at the soonest opportunity to children with severe flu symptoms," Finelli says.