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Influenza: The Burden of Disease in Children

It’s often unrecognized.

The burden of influenza infection in children is unknown. In a multisite cohort study, investigators prospectively enrolled children younger than 5 years who either had been hospitalized or who had presented to clinics and emergency departments in 2000–2004 with symptoms of acute respiratory tract infection or fever. Infection was confirmed by a positive polymerase-chain-reaction assay or viral culture for influenza A or B.

Among 2797 hospitalized children, 6% had laboratory-confirmed influenza. Infection was significantly more common in infants (age range, 0–5 months; 49%) than in older children (age range, 24–59 months; 20%). Among children aged 6 months and older, fewer than 25% of parents reported that their child had been vaccinated against influenza. Only 28% of confirmed cases had discharge diagnoses of influenza. The annual hospitalization rate associated with influenza averaged 0.9 per 1000 children and was significantly higher in infants than in older children (4.5 vs. 0.3 cases per 1000).

Among 1742 children seen in clinics or EDs, 16% had confirmed influenza. Infection was significantly less common in infants than in older children (7% vs. 52%). Among children aged 6 years and older, fewer than 30% of parents reported that their child had been vaccinated. Only 17% of confirmed cases had discharge diagnoses of influenza. During the 2002–2003 influenza season, influenza infection was associated with 50 clinic and 6 ED visits per 1000 children. Corresponding numbers for 2003–2004 were substantially higher (95 and 27 per 1000).

Comment: This is the most comprehensive active prospective surveillance to date of confirmed influenza infection in children. The finding that influenza infection is common, and varies by age and year, is not surprising. In 2004, the CDC recommended that all children aged were 6 to 23 months be vaccinated for flu. As vaccination rates rise, the burden of disease will decline. An editorialist notes that antiviral medications can reduce complications and the spread of disease and calls for clinicians to be more proactive in screening for influenza infection during flu season.

— Howard Bauchner, MD

Published in Journal Watch Pediatrics and Adolescent Medicine July 26, 2006

Citation(s):

Poehling KA et al. The underrecognized burden of influenza in young children. N Engl J Med 2006 Jul 6; 355:31-40.

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Glezen WP. Influenza control. N Engl J Med 2006 Jul 6; 355:79-81.

• Original article (Subscription may be required)
• Medline abstract (Free)