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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., Competing Interests: Potential conflicts of interest. K. P. O. reports grants from Foundation for Atlanta Veterans Education and Research (FAVER) during the conduct of the study. K. Y. H. reports receiving grants from the CDC Emerging Infections Program (EIP) and receiving an hororarium for an invited lecture to the Biology Department at Western Connecticut State University regarding coronavirus disease 2019 (COVID-19) surveillance, outside the submitted work. M. L. M. reports grants and support for travel from the CDC EIP, during the conduct of the study. S. K. reports grants from the Michigan Department of Health and Human Services, during the conduct of the study (Council for State and Territorial Epidemiologists federal grant). R. L. reports grants from the CDC EIP cooperative agreement, during the conduct of the study; receiving royalties as coeditor for a book on infectious disease surveillance (donated to the Minnesota Department of Health); and serving as an associate editor for the American Academy of Pediatrics Red Book (proceeds also donated to the Minnesota Department of Health). C. S. reports receiving grants from New Mexico Department of Health, during the conduct of the study. E. A. reports receiving grants from Pfizer, Sanofi Pasteur, MedImmune, PaxVax, GlaxoSmithKline, Merck, Janssen, and Micron and personal fees from Pfizer, Sanofi Pasteur, and Medscape, outside the submitted work. His institution has also received funding from the National Institutes of Health to conduct clinical trials of Moderna and Janssen COVID-19 vaccines. He also serves on a safety monitoring board for Kentucky BioProcessing and Sanofi Pasteur. L. B. reports receiving grants from the Council for State and Territorial Epidemiologists and the CDC, outside the submitted work (recipient of Epidemiology and Laboratory Capacity and Immunizations and Vaccines for Children grant funding from the CDC to support vaccine preventable disease epidemiology staffing). A. T. reports receiving grants from the CDC EIP cooperative agreement, during the conduct of the study. H. K. T. reports receiving grants from the CDC, during the conduct of the study. W. S. reports grants from the CDC EIP cooperative agreement, during the conduct of the study, and personal fees from VBI Vaccines, outside the submitted work. I. R. reports that her institution has received grants through the Influenza Hospitalization-Based Surveillance Project. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Laboratory testing results are often used to monitor influenza illness in populations, but results may not be representative of illness burden and distribution, especially in populations that are geographically, socioeconomically, and racially/ethnically diverse., Objectives: Descriptive epidemiology and chi-square analyses using demographic, geographic, and medical condition prevalence comparisons were employed to assess whether a group of individuals with outpatient laboratory-confirmed influenza illness during September-November 2009 represented the burden and distribution of influenza illness in New Mexico (NM)., Patients/methods: The outpatient group was identified via random selection from those with positive influenza tests at NM laboratories. Comparison groups included those with laboratory-confirmed H1N1-related influenza hospitalization and death identified via prospective active statewide surveillance, those with self-reported influenza-like illness (ILI) identified through random digit dialing, and the NM population., Results: This analysis included 334 individuals with outpatient laboratory-confirmed influenza, 888 individuals with laboratory-confirmed H1N1-related hospitalization, 39 individuals with laboratory-confirmed H1N1-related death, 334 individuals with ILI, and NM population data (N = 2,036,112). The outpatient laboratory-confirmed group had a different distribution of demographic and geographic factors, as well as prevalence of certain medical conditions as compared to the groups of laboratory-confirmed H1N1-related hospitalization and death, the ILI group, and the NM population., Conclusions: The outpatient laboratory-confirmed group may reflect provider testing practices and potentially healthcare-seeking behavior and access to care, rather than influenza burden and distribution in NM during the H1N1 pandemic., (© 2013 John Wiley & Sons Ltd.)

Histopathologic features of New Mexico 2009 H1N1 fatalities have not been representative of those reported nationwide. We retrospectively reviewed medical records of all New Mexico 2009 pandemic influenza A (pH1N1) fatalities (n = 50). In cases in which autopsy was performed (n = 12), histologic sections and culture results were examined. In contrast to previously published studies, the majority of our fatalities did not have diffuse alveolar damage (DAD) (2/12; 16.7%). Common findings included pulmonary interstitial inflammation and edema, tracheobronchitis, and pneumonia. Two cases had significant extra-pulmonary manifestations: myocarditis and cerebral edema with herniation. The majority had a rapid disease course: range from 1 to 12 days (median, 2 days), and Native Americans were disproportionately represented among fatalities. These findings suggest that New Mexico H1N1 fatalities generally did not survive long enough to develop the classic picture of DAD. Pathologists should be aware that H1N1 may cause extra-pulmonary pathology and perform postmortem cultures and histologic sampling accordingly., (© 2012 American Academy of Forensic Sciences.)

Objectives: We assessed risk factors for 2009 pandemic influenza A (H1N1)-related hospitalization, mechanical ventilation, and death among New Mexico residents., Methods: We calculated population rate ratios using Poisson regression to analyze risk factors for H1N1-related hospitalization. We performed a cross-sectional analysis of hospitalizations during September 14, 2009 through January 13, 2010, using logistic regression to assess risk factors for mechanical ventilation and death among those hospitalized., Results: During the study period, 926 laboratory-confirmed H1N1-related hospitalizations were identified. H1N1-related hospitalization was significantly higher among American Indians (risk ratio [RR] = 2.6; 95% confidence interval [CI] = 2.2, 3.2), Blacks (RR = 1.7; 95% CI = 1.2, 2.4), and Hispanics (RR = 1.8; 95% CI = 1.5, 2.0) than it was among non-Hispanic Whites, and also was higher among persons of younger age and lower household income. Mechanical ventilation was significantly associated with age 25 years and older, obesity, and lack of or delayed antiviral treatment. Death was significantly associated with male gender, cancer during the previous 12 months, and liver disorder., Conclusions: This analysis supports recent national efforts to include American Indian/Alaska Native race as a group at high risk for complications of influenza with respect to vaccination and antiviral treatment recommendations.

During the pandemic (H1N1) 2009 outbreak, Minnesota, New Mexico, and Oregon used several surveillance methods to detect associated deaths. Surveillance using unexplained death and medical examiner data allowed for detection of 34 (18%) pandemic (H1N1) 2009-associated deaths that were not detected by hospital-based surveillance.