Epidemiology, Clinical Characteristics, and Outcomes of Influenza-Associated Hospitalizations in US Children Over 9 Seasons Following the 2009 H1N1 Pandemic
Satoshi Kamidani, Shikha Garg, Melissa A. Rolfes, Angela P. Campbell, Charisse N Cummings, Julia C. Haston, Kyle P. Openo, Emily Fawcett, Shua J. Chai, Rachel Herlihy, Kimberly Yousey‐Hindes, Maya Monroe, Sue Kim, Ruth Lynfield, Chad Smelser, Alison Muse, Christina B. Felsen, Laurie M. Billing, Ann Thomas, H. Keipp Talbot, William Schaffner, Ilene Risk, Evan J. Anderson
Abstract
BACKGROUND: Recent population-based data are limited regarding influenza-associated hospitalizations in US children. METHODS: We identified children <18 years hospitalized with laboratory-confirmed influenza during 2010-2019 seasons, through the Centers for Disease Control and Prevention's Influenza Hospitalization Surveillance Network. Adjusted hospitalization and in-hospital mortality rates were calculated, and multivariable logistic regression was conducted to evaluate risk factors for pneumonia, intensive care unit (ICU) admission, mechanical ventilation, and death. RESULTS: Over 9 seasons, adjusted influenza-associated hospitalization incidence rates ranged from 10 to 375 per 100 000 persons each season and were highest among infants <6 months old. Rates decreased with increasing age. The highest in-hospital mortality rates were observed in children <6 months old (0.73 per 100 000 persons). Over time, antiviral treatment significantly increased, from 56% to 85% (P < .001), and influenza vaccination rates increased from 33% to 44% (P = .003). Among the 13 235 hospitalized children, 2676 (20%) were admitted to the ICU, 2262 (17%) had pneumonia, 690 (5%) required mechanical ventilation, and 72 (0.5%) died during hospitalization. Compared with those <6 months of age, hospitalized children ≥13 years old had higher odds of pneumonia (adjusted odds ratio, 2.7 [95% confidence interval, 2.1-3.4], ICU admission (1.6 [1.3-1.9]), mechanical ventilation (1.6 [1.1-2.2]), and death (3.3 [1.2-9.3]). CONCLUSIONS: Hospitalization and death rates were greatest in younger children at the population level. Among hospitalized children, however, older children had a higher risk of severe outcomes. Continued efforts to prevent and attenuate influenza in children are needed.