The Burden of Influenza Hospitalizations in Infants from 2003- 2012, United States
Chaves, Sandra S. MD, MSc; Perez, Alejandro MPH; et al.
Background: Little information is available describing the epidemiology and clinical characteristics of those <12 months hospitalized with influenza, particularly at a population level.
Methods: We used population-based, laboratory-confirmed influenza hospitalization surveillance data from 2003-2012 seasons to describe the impact of influenza by age category (<3, 3 to <6 and 6 to <12 months). Logistic regression was used to explore risk factors for intensive care unit (ICU) admission. Adjusted age specific influenza-associated hospitalization rates were calculated and applied to the number of U.S. infants to estimate national numbers of hospitalizations.
Results: Influenza was associated with an annual average of 6,514 infant hospitalizations (range 1,842- 12,502). Hospitalization rates among infants <3 months were substantially higher than the rate in older infants. Most hospitalizations occurred in otherwise healthy infants (75%) among whom up to 10% were admitted to the ICU and up to 4% had respiratory failure. These proportions were 2-3 times higher in infants with high risk conditions. Infants <6 months were 40% more likely to be admitted to the ICU than older infants. Lung disease (adjusted odds ratio [aOR] 1.80; 95% confidence interval [CI] 1.22, 2.67), cardiovascular disease (aOR 4.16; 95% CI 2.65, 6.53), and neuromuscular disorder (aOR 2.99; 95% CI 1.87, 4.78) were risk factors for ICU admission among all infants.
Conclusions: The impact of influenza on infants, particularly those very young or with high risk conditions, underscore the importance of influenza vaccination, especially among pregnant women and those in contact with young infants not eligible for vaccination.
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