Influenza-Associated Pediatric Deaths in the United States, 2010–2015

ObjectiveTo characterize and describe influenza-associated pediatric deathsin the United States over five influenza seasons, 2010–11 through2014–15.IntroductionCommunity influenza infection rates are highest among children.In children, influenza can cause severe illness and complicationsincluding, respiratory failure and death. Annual influenza vaccinationis recommended for all persons aged≥6 months. In 2004, influenza-associated deaths in children became a notifiable condition.MethodsDeaths that occurred in children aged <18 years with laboratory-confirmed influenza virus infection were reported from states andterritories to the Centers for Disease Control and Prevention on astandard case report form. We used population estimates from theU.S. Census Bureau, 2011 to 2015, to calculate age group-adjustedincidence. We used Wilcoxon-rank-sum test to compare medians andchi-square and Mantel-Haenszel chi-square to compare differencesbetween proportions of two groups.ResultsFrom October 2010 through September 2015, 590 influenza-associated pediatric deaths were reported. The median age at timeof death was 6 years (interquartile range, 1–12 years). Half of thechildren (285/572) had at least one underlying medical condition.Neurologic conditions (26%) and development delay (21%) weremost commonly reported. The average annual incidence rate was0.16 per 100,000 children (95% confidence interval [CI]: 0.15–0.17)and was highest among children aged <6 months (0.75, 95% CI,0.60–0.94 per 100,000 children), followed by children aged6–23 months (0.34, 95% CI, 0.28–0.41 per 100,000 children). Only21% (87/409) of pediatric deaths in children≥6 months had evidenceof full influenza vaccination. Vaccination coverage was lower inchildren aged 6–23 months (15%) and 5–8 years (17%) than withthose aged 2–4 years and 9–17 years (25%, p<0.01). The majorityof children aged <2 years who died had no underlying medicalconditions (63%, 105/167); this proportion was significantly higherthan that in children aged≥2 years (45%, 182/405, p<0.01).Overall 65% (383) of pediatric deaths had influenza A virusdetected, and 33% had influenza B virus detected. Children infectedwith influenza B virus had a higher frequency of sepsis/shock(41%, 72/174), acute respiratory distress syndrome (ARDS, 33%,58/174), and hemorrhagic pneumonia/pneumonitis (8%, 14/174) thanchildren infected with either influenza A(H1N1) pdm09 or influenzaA(H3N2) virus (p=0.01, 0.03, 0.03, respectively).Overall 81% (421/521) of children had an influenza-associatedcomplication; the most commonly reported were pneumonia (40%),sepsis/shock (31%) and ARDS (29%). Among those with testingreported, invasive bacteria coinfections were identified in 43%(139/322);β-hemolyticStreptococcus(20%) andStaphylococcusaureus(17%) were reported most frequently.Most children (39%, 212/548) died within 3 days of symptomonset, 28% died 4–7 days after onset, and 34% died≥8 days afteronset. The median days from illness onset to death for children withan underlying condition was significantly longer than the time forpreviously healthy children (7 versus 4 days, p<0.01).ConclusionsEach year, a substantial number of influenza-associated deathsoccur among U.S. children, with rates highest among those aged<2 years. While half of the deaths were among children withunderlying conditions, the majority of children <2 years who diedwere previously healthy. Vaccination coverage was very low.Influenza vaccination among pregnant women, young children andchildren with high-risk underlying conditions should be encouragedand could reduce influenza-associated mortality among children